I really don't care about autofill but I acknowledge that it is more of a bandaid solution than a proper one.
Even with autofill, you are still playing your preferred role more than not, whereas before role pick was a thing, it was completely up to luck what role you got to play at all unless you were first pick, and even then, it was often better to give up your role so that another person could do it since they were incapable of fulfilling the role they ended up with and you playing a role you can play decently while they play one that they are at least comfortable with is better than you playing your best role and them feeding on theirs.
With the chances of people not getting their role outside of ending up playing support being virtually nonexistent, really all you need to do is learn to play at least one pocket support and be done with it, whereas before you had to learn every role in the game just so you could manage whatever you ended up with.
Also, I am a Mid/support main so i don't even notice autofill when it happens. :P
Having played sinne season 3, i can play at least 5 champs in every position. Autofill is not even close to a problem to me.