I'm fairly sure the randart changes went into .16, so this isn't just limited to .17 games, by the way. Here's a normal, general case .16+ randart
-1 cloak of Weightlessness {rElec rF+ rC+ Str+3 Dex-4}
ring "Emaczeh" {rN+ MP+9 Str+4 Int-2}
This is fairly typical of the new randart style: strong positives, with some downsides (-1 armor enchantment, and the negative dex). Still overall very usable. The ring has some decent properties and one negative one.
General case for .15 and before:
+3 pair of boots of the Flute {Str+3 Int+3}
+1 buckler of Defence {+Rage Dex+2 Slay+5}
All positives, not too many of them, but solid items. Then there's the things that just weren't possible before:
+2 robe "Dacesh" {rElec rC+++ Str-3}
Having three pips of a resist is something I don't think old randarts could do. This isn't actually that strong (it'd be better to have rC++ and rF+), but it has a psychological impact on players (or at least me). Similarly, regen and + mana on gloves/boots/etc:
+1 pair of gloves "Jerphunai" {rF- rC+ Regen+ Int+3 Slay-3}
With the -slay and rF-, they aren't that great of a pair of gloves, but getting regeneration on gloves is something new you couldn't do before, so it feels strong.
It seems to be reasonably common to get things that have their one obiligatory negative, and then a whole ton of great mods as well (these are all from one game):
amulet "Haacet" {rMut rPois rC++ Dex-4 SInv} (curse)
ring of Xollio Fohu {rElec rF++ rN+ MR+ Str+4 Dex-2}
ring "Stey" {rElec rC+ rN+ Int+5 Dex-4 Slay+3}
Apparently dex was my dump stat. Never noticed how those all lined up
Conclusions: I'm not sure that randarts are any stronger than they were before on average, but there are new properties that couldn't generate before, like regen or +11 dex, which certainly feel strong. I do think if you get a particularly lucky randart it is better post .16 than pre .16, but not hugely so. Still, getting a ring with -2dex isn't really going make it significantly worse when it has 6 positive properties as well (ring of Xollio Fohu above, counting rF++ as two properties). I don't think this has to be nerfed, but if it was tweaked slightly down, that would probably be fine too.