I am completely baffled by your statements. You are entitled to your opinion, but I just dont understand these points at all.
If any game is bland and generic it is Diablo 3. There isnt an interesting element to the entire game. The main quest is complete crap, the entire game is leveled, and all those skills are basically the same.
Loot is better since they stopped trying to make money off of it but still boring despite uniques dropping all the time.
The core experience of D3 is pathetic. It is 100% grind. And there is really no difficulty scale just a speed of clearance scale which is why people say play either Torment II or Torment X because of the RATE of obtaining legendaries. Nephalem Rifts and Greater Rifts are incredibly banal and boring.
The skill system and the skills themselves are mind numbing-ly homogenized and scaled. Paragon levels are a great idea but the implementation is as boring as possible.
Sad thing, is D3 at the first Blizzon was AWESOME. Almost perfect and the additional depth they planned was fantastic. But then the game got shallower and shallower and shallower until in the Beta literally all they did was remove feature after feature until nothing was left. And Loot 2.0 is just lipstick on a pig. Diablo 3 is a terrible game.
TL2 WAS better than D3. Titan Quest and Grim Dawn are both better than D3. But the reason they do not have longevity is simple. They do not have a persistent online presence with league play and exploit controls. These things cost more though than the entire budget of a TL2 or a GD, so they dont exist. So POE and D3 will have longer longevity than GD but for only this reason.
And I have played D3 quite a bit. I really want to like it. D2 was and is one of my favorite games ever, but outside of graphics and animations (they are fantastic in D3) D3 is an incredibly shallow and very boring shell of a game.
It all comes down to taste
You seem very emotionally invested against D3 in ways that have nothing to do with the actual gameplay - and your statement is peppered with little attacks at their philosophy. Also, if you really think an earlier incomplete version was, somehow, better without a doubt - it kinda tells me you're basing that on your imagination rather than reality - and imagination is always better when it comes to games.
I don't personally care about games being online or offline - as I'm always online. I can disagree with games that force online for no good reason, but I still wouldn't care much. But I understood the reasons Blizzard had for going that way.
I understood and agreed with the concept of RMAH - and I'm sad they got pressured into removing it.
As for scaling skills - that's pretty standard for the genre, and it's true for all the other games we're talking about. As for homogenized - I guess there's always that argument in any game, but at least Blizzard understands that skills should not only behave differently - they should look and sound very distinct. Something that Grim Dawn doesn't seem to strive towards. Anyway, all skills tend to do only a handful of things in any game - including buff, debuff, heal, damage, boost speed, etc.
I doubt you'd find a game that breaks that kind of barrier anywhere.
The key is whether the skills play out differently - and I think they do that very much in Diablo 3. Especially when you consider just how many active skills they've managed to put in there.
That said, obviously Blizzard has a much larger team and much more experienced artists - so it's not necessarily a fair comparison.
Grim Dawn has a small portion of actives that repeat from characters to items - and the rest are passive boosts. That's cool and all, but it doesn't excite me much.
That said, I'm not happy with how weapons are largely "DPS sticks" with minimal differences - and that's one of the worst parts of the D3 design.
That was one of the best things about Hellgate and Borderlands - where weapons - at the core - were truly different.
As for Torchlight 2, that was a nice little game with a few neat features. But I have to laugh at your problem with the D3 story when you think of how shallow TL2 is. Talk about being grind only.
Let's not kid ourselves - the entire genre is and always has been about grinding once you get through the content. Grim Dawn is most certainly no different here. So that criticism is pretty invalid.
As for the story in the campaign, I tend to agree it's pretty bad. But the presentation and level of immersion is much, much higher than the bland generic text splashes in Grim Dawn. The recent voice acting didn't help much - as they sound pretty unengaged.
I don't participate in leagues or anything of that nature. The reason I still play Diablo 3 is that I still think it's fun - that's all.
Grim Dawn gave me around 40 hours all in all - and I doubt I'll play much more than that. It's just that dull.
Path of Exile is the better of the alternatives - because of its much more in-depth character system and skill system. But it just can't match Diablo 3 in terms of loot and core gameplay.
Anyway, it all comes down to tastes.