There are are pretty good ways to mitigate it ... or at least deal with it, Using transports, levelling units up (Drukhari receive more benefits than usual from that) or using drugs with associated research - or all that AND buying defensive items for your heroes should help immensely.

I need more experience with them, but with the right effects they can apparently be sort of hard to kill - at least in the turn after exiting a transport (you can research buffs for that).

Both sorts of Eldar ARE still kind of squishy though ... at least in their natural state and Craftworld Eldar appear to have the tougher vehicles ,,, and are generally perhaps a little tougher than Drukhari.
On the other hand, as Drukhari, you are pretty safe ... once you kill all the enemies in your vicinity ... and Drukhari are excellent at that. :)

Originally posted by MaximB:

I read in the Drukhari dlc comments\reviews on Steam that Drukhari faction is very squashy,

Skill issue.
No, honestly: Skill issue.
Such reviews are normal as soon as a new faction/race/empire in any similar games appears that plays differently than those factions some people are accustomed to. Suddenly those new factions are either perceived as being OP or too weak.
The truth just is: They are Eldar and thus you have to play them differently than Space Marines or buffed up Orkz.

Eldar in general are fragile, pointy-eared degenerates. But what they lack in resistance, they make up for in ways to kill the opponent quick (and dirty in case of the Dark ones). I consider them pretty balanced. Just play to their strengths: Mobility and swift strikes.
You can try to tank with them, but then you should have a working unit rotation. And a lot of units to mitigate the waiting turns to bring back HP. So - better avoid tanking in the first place.

Originally posted by MaximB:

But has this issue been fixed since release?

There's nothing to be fixed.