While I agree that fully painted models are friggin' awesome looking on the table, if I was required to have painted models or penalized via rules for less than 4 colours in casual games at a location: I would find another location to game at.
Whilst i'd still consider our group casual i did mention that we only apply those rules for apocalypse games, and our apocalypse games tend to be a 3-4 day event with a year long wind up. The last apocalypse game we played ended up with only a single unit effected by naked model syndrome, a cultist squad that the owner had run out of time to get done, and they were dead in the first turn anyway.
As someone who also finds the painting the most annoying part of the hobby; I'd rather spend all my time converting and get someone else to paint them if i could afford it, i kinda see where you're coming from. But i can't really understand the logic behind turning down a massive, visually stunning game with half your army to instead not play anything.
I mean the painted portion of my ork army is about 10k at the moment but i've still got 150 infantry, 30 vehicles and 7 superheavies sat in the wings waiting for me to get to them. It doesn't upset me that i can only field 10k instead of 25k because i know that once i've fought my way through those models, the game will be even bigger and better.
It's also a good way of balancing out those who have greater disposable incomes, stops them buying up an entire army of stuff, 3 weeks before the game, in an effort to try and unbalance the teams.
We've even worked out ways of balancing the sides to ensure that players with smaller armies don't end up wiped out and bored early on. Basically we work out the combined points total on each side (disorder/order) and then divide it equally between the players on that team. Obviously people use units from their own army first but where players have significantly less points they'll end up supplemented by controlling units from the larger forces on their team.
Not really the mean spirited bullys you seem to have decided our group was. more that we like to ensure that our annual, apocalypse, blowout looks as spectacular as possible as well as being fun to play.