Buy them only if you REALLY need everything with the B5 label on it.
A bit too harsh - at least for most of the minis. It's true that some of the EA characters and all of the (fiurst made, but last released) promotional minis (except Kosh) are rather sub-standard, yes. G'Kar Does have too big a head, true. Delenn does look kinda funny, right.
But the others... from Morden to Kalain, from Vir to the Gaim ambassador, from Ivanova to the Soul Hunters, they'd compare nicely to many, many other minis out there. Of course I've seen better (Hmmm... Ral Partha...), but I have also seen worse, much worse.
In the end, yes, a few very bad ones could use a resculpt if Mongoose would manage to bring them back as character minis. The rest though would provide a great basic stock to build from...
(And I really hope they do manage that - I would like nothing more than have more then a handful or Aliens; after all, human minis matching them in scale are not too hard to find, but getting more Narn would be hard... and I would Really like two Shadows to flank my Morden mini...)