This is actually something I wanted to make a topic about as well because this concept is of particular interest to me, being an avid gamer (and chess player) I always get a sour taste in my mouth when 'hax' happens, in pokemon and/or other games.
Pokemon is a game of imperfect information. If you aren't exactly sure what that means, it means that in order to make the optimal decision, you require information that is not (currently) available to you. Poker is a great example of a game with imperfect information - you do not know the hand of the other player and are thus unable to make the true optimal decision, so what you will do instead is make the optimal decision based on the information that you have available to you. Then you have games with pseudo-perfect information - all the information you need is right there, but due to time constraints you may not be able to react to the information in time to make use of it. This is shown in fighting games such as Street Fighter, where it is simply not humanly possible to react to 100% of the opponent's actions. A game of truly perfect information would be chess.
The problem with the hax-free version presented in the topic is that the game is currently balanced around having this 'hax'. Boosting moves would be much more powerful with the absence of critical hits or even secondary effects such as paralyze from thunderbolt. You generally want to swap into something that allows you to set-up, but there are plenty of situations where one crit could ruin your day which would make the strategy of +6/+6ing a pokemon unfavorable. I want you to go back to 3rd gen (adv) and think of Celebi with Calm Mind and Recover. STAB on Ice Beam was relatively rare, but it was still super-effective against Celebi. However, due to carefully managing Celebi's CMs and Recovers, you could actually become incredibly strong if it wasn't for the freeze and/or critical hit chance. Strategies like these would become much more powerful and/or increase the importance of moves such as Leaf Blade (if we follow your 100% crit suggestion). Either way you are messing with the balance of the game and it is hard to foresee how much you'd mess with it due to all the factors.
Another issue is that the lack of crits and secondary effects promote passive play. I don't know if you have ever played 2nd gen (GSC), but I doubt many people would enjoy that. If your strategy relies on swapping out a lot of pokemon and using 'passive' moves such as Toxic, Rest, Swords Dance and so forth, it will be stronger with the suggested changes. Many times I have tried to make elaborate stall teams across the pokemon generations, but swapping Tyranitar into the 5th flamethrower, sludge bomb or ice beam simply wasn't a good strategy despite it taking nearly no damage and allowing me to set up. What if secondary effects were removed? Do we really want to reward passive switch-whorish play?
'Hax' isn't the only problem, however. Let us say that you have any Choice Band pokemon. The pokemon you are facing would get OHKOd by your Earthquake plus you have the speed advantage, but if you stay in and use any other non-OHKOing move, the opposing pokemon can OHKO you if it decides to stay in. Worse, uneducated, naive players call this phenomenon 'mindgames', while in fact it is mostly dumb luck. What you generally end up doing is earthquaking the opposing pokemon because in the worst case scenario he will swap and force you to swap out yourself, giving him momentum. This is the optimal decision if we are assuming that your opponent is doing 50/50, but if your opponent is any good he will not act as if it was 50/50. Let us say that your opponent has two pokemon remaining - Articuno and Aggron, whereas you have CB Rhydon. It is currently Rhydon vs. Aggron and you know for a fact you are faster and can OHKO him with Earthquake. However, he can swap out to Articuno, who you'd definitely OHKO with any rock move. There are basically two decisions (technically 3 - swapping out yourself, but to make my point clear we'll totally ignore this option because it greatly simplifies the maths). You Earthquake to OHKO Aggron, or you use any rock move to OHKO Articuno. What do you do? You will probably Earthquake as that decision is the 'best', meaning that if you got this exact situation for 1000 more times, you'd win in the long run if you used Earthquake, as you either kill a pokemon or have to swap out vs. killing a pokemon or losing a pokemon. Your opponent should know this as well and can therefor adjust. If you're more likely to use Earthquake (which you are as it is 'optimal' assuming 50/50), the opponent is more likely to swap in Articuno, essentially making it a 50/50 guess anyway. This concept is known as WIFOM (read more here: http://wiki.mafiascum.net/index.php?title=WIFOM
If you are removing 'hax', should you also find a way to remove WIFOM-situations? They are everywhere.