I agree seals should be more interesting and important at the baseline but I'm not sure how attack power vs. haste would really be a choice. You'd just go with whatever is mathematically worked out to be higher DPS.
It's been suggested before that tier 90 grant holy power. Could be cool, but for starters it'd be nice if Holy Prism wasn't totally unviable and Light's Hammer did the same amount of damage it currently does but with half the duration.
Can't delete Exo without other changes like 3 sec CS or Hammer of Wrath part of the baseline rotation. Unless I hear an idea I really like I think the best solution is to keep Exo around and to find a way to bump it up in priority. This can be through more damage, Exo gives 2-3 holy power + you can store two charges to not waste Art of War procs, etc.
I'd straight-up delete Hammer of the Righteous. It's just an AoE replacement for CS, nothing remotely interesting about it.
I understand the problem some Rets have with Empowered Divine Storm and I think it was Solascra who said the charge system could work well here, too. I'm not going to delve deeper into that right now, but I'd like to throw out a fanciful idea that's been around for a while: Divine Storm should have a duration and you feed the storm with holy power. Could be the whole ability or an after effect of the direct attack. This wouldn't really solve any problems, just think it sounds cool.
Hand spells: are you saying Ret shouldn't even have them? Can't agree with you there having grown up as a PvP Ret.
They can already be a bit useless in raids assuming you have multiple paladins, which is usually the case. Actually I think Ret should have access to more utility than it does now. Tier 45 in general is pretty useless in raids, with Eternal Flame being a real stinker, and tier 60 would benefit from taking Hand of Purity off the GCD. Not sure why this was done for Sac but not Purity.