Aren't the new top rank keystone masteries really imbalanced?

Just from what I gathered from a PBE patch notes website (which may be wrong) it looks like we have: Tank option: Grants 20 health per siege and 8 health per large monster to a maximum of 250 bonus health (permanent). Once max health is reached, nearby siege minions dying restore 100 health.

Offensive options: 3 hits = flat per level + %AD and %AP damage applied to enemies in the area as a DoT or Damage does %AD and %AP damage as a DoT to afflicted enemy

Utility option: Grants movement speed if you do more than enough damage to an enemy champion.

So, my problems with this: Both offensive options are % scaling. It comes down to whether you want an AOE DoT or a targeted DoT. Have a team with loads of AoE CC? AoE. Otherwise? Targeted.

The only tank option is flat and offers sustain. Firstly, reduces a lot of the power of having sustain in your kit. Secondly, since it's flat, tanks will be even more obliterated by damage dealers late game than they already are. It's already easy enough to blow people up - so this seems imbalanced...

The only utility option requires you to do enough damage to CHAMPS to get the MS. So it's basically an offensive option for assassins that want to get in and out.

Where is the option for supports? Sure, a tank support can take the tank option, but other supports probably won't have the damage to take any of the other options...

Why are tanks being put even farther behind? Juggernauts / Bruisers already seem way more useful, and now they'll get a scaling mastery whereas tanks get a flat one. The sustain will be nice at least I guess.

Also, the whole entry of wanting masteries to match your playstyle, etc... I don't really see much choice happening here. Damage dealers want damage and will take the damage mastery based on their team. There may be a few niche spots for the utility mastery. Anyone else is stuck with the tank mastery that is really underwhelming by mid game (250 health really isn't much once you have a couple defensive items, and for the sustain, siege minions only come every 3 waves...). It will also take 36 waves to get 12 siege minions for 240 health assuming you last hit every one and don't do jungle camps in between. That's 20 minutes in to the game to get 250 health - basically worthless in my opinion...

I don't even see what was wrong with the current masteries anyways... maybe there were common choices but they still varied from game to game in some cases, and while they didn't have huge impacts I didn't think they really should. I don't think a mastery selection should really be apparent in the game. I don't want to 1v1 an opponent and win and have the opponent be like "oh, I lost because he took mastery X". Like maybe I got a kill because I took spell weaving and blade weaving while you took % bonus AD - that shouldn't be obvious though, it's better to just think I outplayed the fight and measured the result better.