In 4 man content, I'm amusingly still entirely MP limited for the most part. That's with Piety/Crit melds on the left side (VIT on the accessories).
In raid content, the occasions where I find myself hurting for MP are usually because I've forgotten to hit Thin Air despite keeping Assize on CD like clockwork. In all honesty I think it's a significantly more powerful MP tool than Assize once you get the hang of remembering to use it.
Nerfing WHM's MP economy isn't a good idea if you ask me though. Remember that in reality, WHM actually hasn't changed much from 3.4 at all where it was pretty much regarded as the weakest of the 3 healers and by a fairly unhealthy margin, nobody wants to see the job return to those depths. If you're sitting around on full MP all the time I'd suggest looking at your APM first and going from there, chances are you're wasting windows of opportunity.