What I'm trying to do is not particularly argue for Spikes on Malaconda, but to get down to the details as to why there is opposition to such a move.
The worry (or my worry) is that it very much makes it exceptionally difficult to handle sun. Lets recap here, sunlight is the ONLY weather on the table, where you can run its speed boosting ability along side it (for reference im talking Cloro here) AND get a STAB boost for some of your abusers. This is already, pretty darn massive, but sunlight is held back by its sub standard abuser, SR weakness, and lack of pivots. Malaconda changes all of this, by giving sunlight an awesome spinner AND making it an excelelnt pivot. Its also happens to check most of the common sun problems (Sun vs Rain is now less of a skill matchup).
Looking at this, its already boosting sun up to the level of Sand and perhapes sunlight. Its given sunlight its own "Ferrothorn" - a bulky pivot that happens to have reliable recovery. What people are pushing for now is adding Spikes on top of this, and I feel that it goes too far as suddenly, you jack up the difficulty of beating sunlight, its now not enough to simply chuck on a Latios and win, now you seriosuly need to devolop ways of defeating Malaconda, as well as the sun team. On top of this, you need to worry about Spikes crippling your Tyranitar, or your Hippowdon, sunlight already has Dugtrio for Stealth Rock, imagine taking damage from a layer of Spikes and Stealth rock as well!
Its not like Sun is easily spinable eaither, you cannot spin on Malaconda, its OHKOing Starmie, and Tentacruel loses (also Dugtrio can take it out when weakened) 1v1. Venusaur outspeeds Starmie, and gets a free set up on Tentacruel that lack Ice Beam (even then its got Giga Drain), Dugtrio can and will trap those spinners when they are low enough, heck, Tobes proved you can run fucking Chandelure on your sun team and presto! You have a spinblocker! Thoughout all of this remember, you have a Spiker, with massive bulk, with a 100% recovery move. Deoxys-D doesn't have this, Forretress doesn't have this, nor do Skarmory or Ferrothorn. All of the above can and do set up Spikes over the course of a match with ease, (Yes even in a spinner dominated metagame). The moment you add Malaconda into the mix, its very difficult to stop it setting up, then spinning and not dying, and then stopping it from setting up even more, bearing in mind it has flat out amazing bulk AND awesome recovery. Its a tough ask.
To be clear here, I am not for one single second, claiming that Spikes on Malaconda is 'broken", because its not really. The issue I have, is that giving Sun an amazing pivot such as Malaconda, with amazing recovery, with an already amazing support movepool, a CAP
designed to counter the biggest problems to sunlight in this metagame, and you want to give it Spikes on top of this, which makes sunlight even more difficult to stop. Suddenly you have Politoed lose 1v1, you have Tyranitar sorta lose (PW does way 2 much PLUS if it ever gets a kill its Dug Bait), so you have um, Hippowdon I guess which is Spike fodder AND doesn't like Power Whip (or Toxic which it has) anyway. Furthermore, a case could potentially be made that Spikes hampers out concept, since suddenly, you are not just affecting the usage of water types, and dragons, suddenly your heavily affecting the usage of grounded pokemon, which DO drop when spikers such as this are popular, since players want to minimise the damge they take from switching. We are already targeting Most water / dragon / Steel (since we are increasing the usage of sun, I fully expect SOME steels to drop in usage) types, are we expanding this to most of the OU viable pokemon that are hit by spikes as well? (Worth noting that currently most of Malaconda's best checks and counters are hit by Spikes as well, giving it the chance to easily outlast them).
Sorry for the tl;dr I was in a rush