Anytime you get too many dots specs have problems with most modern raid mechanics. IE if you have 5x dots and no SB:SS you are talking a minimum of 5x gcd's to get them all up to even start doing your damage. In the proverbial vacuum of balance the more dots you have the less each one does when you are balanced. Those mechanics really take a hard hit when you need to target swap, burst something, etc which is a reality of modern raiding. Remember h.spine?
I don't mind passives where a nuke procs a dot (firemage nukes, HoG, etc) but that is a different thing all together. In that way I wouldn't mind losing corruption for demo and extending shadowflame about 6 seconds. That would reward people who were good with their HoG stacking/weaving and corruption just doesn't feel like it has a place anymore. Plus anytime a spell is shared between specs it can be a balance issue. Corruption does so little in terms of damage now its basically just a DF source. (about 12-15% per sims and only about 3% damage done) I'd rather reward good play on HoG and let aff have its classic dots. Demo to me is fun for its pets, form(s), and balance of how to generate AND spend DF. Corruption really doesn't figure into that besides being a vestige/DF engine.