I'm also someone who spent 100s of hours to get good IV Pokemon... and I'm really happy about Hyper Training being able to change / increase IVs.
Breeding or softrestting is probably the most boring and time consuming time-waste I had in my life (and I'm 28; been SRing since RBY and throughout all generations).
I have over 1300 hours on my Alphasapphire, ~30 of it is probably playing normally through the story and catching Pokemon (I have a living Dex too).
I have basically 8 full boxes of competitively bred and trained Pokemon (mostly 5 perfect IVs, since most of the time the 6th one isn't needed anyway), all bred myself. And I'm still trying to catch all legendaries in XYORAS with good IVs and natures (there are still A LOT of them missing).
Out of breeding and softrestting, this is probably the order on how annoying these things are:
- softresetting for an internet-event poke (since you can't influence the nature); super annoying since oftentimes you get great IV spreads, but not the right nature - and when you finally get the right nature there's always something off too much.
- softresetting for legends you have to catch; only 50 % chance for synchronize to work, some have super annoying sequences shown which you have to get through, and then you have to lower their HP / put them to sleep, throw many many balls and hope for the best. This is especially annoying if you want one with a specific Hidden Power (I'm super proud of my great Thundurus with HP Ice which is almost perfect). It's waaay too annoying and time consuming to always have to wait so much for catching them. That's why I'm trying to collect a lot of IDs from wonder trade to get lucky in the lottery and the "pick something up" ability from 5 friends in my secret bases (I have both omega ruby and alpha sapphire). Checking all of this daily in hope of getting lucky.
Yeah- legends are supposed to be hard to catch, and it's a good thing, but the problem is getting a good one is just too boring and wasting too much time. Most competitive players don't even do this and just Gen/RNG them anyway.
- breeding; it's suuuuper boring and time consuming, but at least you get closer and closer over time. Some parents can be used for other Pokemon etc. so it's really getting better and better. It still takes hours and hours of just holding up and pressing A and being frustrated over almost-perfect ones. So in the end it's just a endlessly boring thing to do. It's kinda fun- for a little bit. But then you want the right Hidden Ability and gender and then it's becoming super stupid (especially for Pokemon that have a 12.5 % chance of the right gender). Some genderless Pokemon are super annoying too, since you need to have a 5 or 6 IV Ditto (which "normal" people can't usually get by themselves).
Pokemon from previous Gens often aren't good enough:
In Black/White I bred some Pokemon and have like almost a box full of them. They all have 2-4 perfect IVs (mostly 3). So they were basically all useless when XY came around since it was possible to get pretty much perfect ones. For anyone who wasn't RNGing or PokeGenning or whatever it was almost impossible to get even any near perfect Pokemon.. so having gotten the new options in XY was amazing!
I got one perfect 'mon by breeding in White, though. A perfect 6IV Squirtle with Water Spout, I was really happy, but it was just a breeding parent for the newer games, since some new Egg Moves are kinda needed.
So basically they often give Pokemon new tools (abilities, egg moves, ..) which makes you having to rebreed them anyways. Now if they kinda "force" you to rebreed all of them again (so they're from Sun/Moon) that makes it super annoying having to do most of the work again.
Also, who didn't have "almost perfect" or "okay" shinies bred that maybe came too early (before I had bred better parents)? Or legends with "just" 3 or 4 perfect IVs [basically all of my gen6 legends since I don't RNG]? It's just SO much time saving that they finally give you something to "fix" these almost perfect Pokemon.
Hyper Training:
Though I don't get why they made it so you can only use Hyper Training to change IVs when your Pokemon is level 100... I mean it kinda makes sense as a final reward you get for fully levelling up, but since XY they basically tried to give all the Pokemon upon reaching level 50 everything they need. And basically all battle competitions were held at level 50.
Every move you'd need can be gotten by Heart Scales, Move Tutors or Egg Moves. Or they just learn them earlier. I could basically get all needed moves by level 50 for every Pokemon. The only ones that are higher are ones that evolve later like Hydreigon or Tyranitar, etc. So it's just kinda a hustle having to level them up further. Levelling to lvl 100 will take quite a bit of time and who knows how exactly the hyper training works... it could take more time than Super Training and even getting the Bottlecaps could take time like them being sold for like 100 Battle Points or something. Also I think it would be good enough if they raise IVs by 1 (maybe you only get something like "Bronze Bottlecaps" endlessly ingame). That would make it easier to get better Hidden Powers too (though tbh I think you should be able to change it seperately with a move tutor or something similar, and not have it influenced by IVs).
It'll take a looot of time to train all these Pokemon to level 100 now, and then you have to get all the money/BPs/whatever to get these Bottlecaps and then you still have to "Hyper Train" them.
So basically I think it's not worth it over breeding normally. Maybe a few times for Ditto, shinies, legends or genderless Pokemon. Which is perfectly fine. Though to be fair I'd also don't mind something that changes natures. Give me all them options to save some time (I'd mostly want it to "fix" some legends or shinies, or maybe switch sets around for Pokemon I have already trained). I'd rather battle than spend 1000s of hours of breeding and softrestting, basically just sitting there and pressing the same button and not even looking at what I'm doing.
Making people able to get all Pokemon perfect without cheating and without spending half their life on it is a great thing.