So basically it is an ARPG?
Look, D3 is in the best state that it has ever been in. Additionally, it is without
any doubt the most polished ARPG on the market currently. As a game type, ARPG's are inherently difficult to garner long term support. You are talking about a massive balance game between giving players upgrades and trying to keep them playing. Give players upgrades too quickly, and they quit due to boredom. Give players upgrades too slowly, and they quit due to a lack of progression. Out of all the games out there, ARPG's are one of the hardest to get right. D3 fucked it hard prior to 2.0, there is really no doubt about this. The game was a complete shit fest (technical term), regardless Blizzard has made an attempt to re-invent the wheel. As a game, as an ARPG, it is without any doubt the best out there.
In the end the biggest problem within the ARPG genre...happens to be the players. OMG, do not stone me. It is true, hurts doesn't it? Players today want instant gratification, they want quick progression, etc. Guess what kiddos, ARPG's are not about instant gratification or quick progression. You aren't getting a new map pack in four months, you aren't getting another DLC drop in six months, grinding is THE game. ARPG's do not mesh well with today's gamer's. Sad, but true.
Figure out what you want out of D3. If you want to level each class to 70, farm up some gear, and hit T1 for a bit; do so. You will be able to do that with relative ease, far easier than ever before. If you are wanting to farm Torment 6, then you are looking at the long haul.
TL
R; D3 is the most polished ARPG on the market. It is in the best state that it has ever been in, this is how the game should have launched. Regardless, it is still an ARPG, if you do not want to grind at all then GTFO.