I can't think of any game that did well that included the base chance for failure in your spells or ablities. Sure, crafting, enchanting, that kind of thing had failure chances, but casting a fireball? never.
I like the idea of the chance of success increasing as the caster becomes more powerful, but giving faster access to mid level casters to the cool stuff. It creates much more varied game flow than the "optimal research path" that almost invevitably devlops in TBS games.
The research path would be exactly the same, you would just get spells in it sooner and be unable to cast them until you were stronger anyway for fear of fizzling them. Getting them earlier and needing to get stronger before casting them to imporve chances of not blowing yourself up mean that the tech is in exactly the same place it was before, only now its more complex and unpleasent.
The primary uncertantiy in tbs games should come from opponets, not your own spells.
But making careful risk/reward assessements in the long term will lead to positive results, even after having to go through several small heart attacks. On the other hand, if you are way behind, at least you still have a chance to get back in, rather than just quitting.
But most people won't bother with careful risk assessments, they will either avoid spells completly or fire them off as fast as they can and hope that at least 51% of the spells work correctly. And the idea of coming from behind by a trick of the RNG is horrifying. If you are losing to a better opponet by a decent margain, you should NOT be saved by the RNG. Any saving should come from the player.
It would allow a newbie a better, albeit still very small, chance of winning a game, which is pretty important when trying to bring new players into the online community.
If i was a newbie at a game, and managed to win by the pure vageries of chance agasint a player who clearly knew what he was doing, i would get out of there fast. What is the point of getting good at a game if you can be beaten by someone randomly clicking who gets lucky with the RNG.
After all that, i do think the RNG is important, it does play a roll, i just don't think it should be able to change the balance of the game. If someone is winning, they should win. And i don't want to see people not casting spells for fear of backfires. Kinda defeats the point of being a channeler.