I've got top renown lots of times as healer (both with Praedor and my lowbie RP alt). Heal the important people (the ones carrying the flag or whatever; or the people whacking the EFC), use group heals when-ever possible, decurse as much as you can -> Renown just keeps raining in.
I do. Every game, I heal -everyone-. It's all I do. I decurse when I can. I always res people. I have
never topped a renown chart. XP I topped once and only once, and I check every single game cause I'm OCD like that. This includes games where I healed for 36k in T1 - Nordenwatch, 96k in T2 - Mourkain Temple and 160k in Tor Anroc.
My feeling is this is unnecessary and has been prompted by skewed results that you get when you leave your scenario group (not that I ever have). That is what should have been fixed, not this blanket renown reduction. They are going to make it so that it's necessary to leave your group in order to reap the same rewards that other classes do simply by playing their class.
I know that to maximise my xp/renown I should be tagging people with DoTs, spamming rune of sundering etc as much as I can - at the expense of heals. I'll do that if I happen to be at full AP, and nobody is taking damage, but that happens so rarely as to be an exceptional case.
That said I'll wait to see the results myself before I proclaim the sky is falling, but I'm a little dissapointed. There are much more pressing issues than this that need addressing.