Combat logs - yes please
Addons - No thanks
Combat logs are great, both for improving and to figure out why your raid hit enrage, who wasnt pulling his weight?
UI modification are also fine as they allow people to chose a visual style that they like
But mods WoW-style is a slippery slope, im all for giving people information - not assisted gameplay
So Combatlogs and damange parser is ok - Healbot's Raidalert and what else they are called not so much