This isn't just Skaven, it's a general problem with neutral races in WH:I. Personally I love Lizardmen, from the war game. However the representation in WHI:I is pretty bad. They only have 2 2-cost units iirc, and while they do have some stronger units they are all so expensive making a Lizard focused deck is disheartning. Also for the race with the most magical talent (yes they out do you HE, don't deny it) in the WH world, they are pretty poorly represented.
I don't think the chaos neutral races are as bad as the order ones. Skaven has the natural advantage of being around longer, even if the card pool is balanced by the custom expansion. Undead/Vampires (I presume these will stay as one category…) seem the strongest, atleast they have more reliable strategies. Wood Elves have a number of forest spirits that are just too expensive and some Wood Elf cards that are somewhat thematic, then a number of cards that don't make a lot of sense in relation to the original themes or tabletop game.
I understand the argument against neutral races - as they are playable in any deck (of the same alignment) they can't be OP or they will be overused. However I don't get why FFG hasn't explored tribal themes. Like the above Skaven unit (Warlock Engineer). Instead of making it cost 4, which renders it almost useless for a 1/1, make it cost 2 and have a requirement that it can only be played in a zone containing another Skaven unit. Similar things could have been done with Forest Spirits… which would make sense for a forest. The always playable theme is lost as the player needs to be running other units of the same type and enough of them to likely have one in play - so tribal strategies are the only forgiving way to play them (I don't believe we have keyword manipulation).
I think, as great as the game is, FFG just looses focus at times on the Warhammer world. It isn't a game with 6 races - there are more, and as FFG has brought these into the game they should be atleast playable instead of filler cards in a battle pack. I wish we would get more tribal cards - to lower cost of neutral units, infer bonus or conditions of playability that suit the both the thematic environment in Warhammer and the pre-existing playstyles originally introduced for each race. And please, don't just think 'we haven't produced any Lizardmen for a while, lets make one with some erratic ability that makes no sense, but since it's neutral it's ok'….
Sorry for the rant, the Warhammer world is something I love and have for a long time. Sadly my favorite races (Lizardmen and Wood Elves) seem like ideas originally placed then forgotten about and other random things thrown on top to make it look like FFG wants to develop the race, if only for the sake of having more neutral cards. The packs seem to be growing in focus, the next cycle looks good, so hopefully this can tie up some loose ends in these races.