Every house doesnt need a battlecruiser, but every house could use two types of cruisers.
sort of 'heres your single cruiser, now lump it!'
Kusari's destroyer is too tiny and they havent got a remotely heavy cruiser. Rheinlands cruiser is practically a battlecruiser and it probably could do with being stat'd like one, provided they were given a lighter cruiser to replace the thruster loss. Bretonia is sort of strange, the bret destroyer isnt huge, but its heavy, they could use a really light cruiser or a BC. Liberty already has two types, which makes it better than the other three houses, on top of having two BS (light and heavy).
Hell, it was someones bright idea that Zoners and Order should have more types of capital ships than houses, with two cruisers and two BS for the zoners, and order with two cruisers. Bounty hunters have two cruisers also, less noticable is the two rheinland unlawful cruisers.
could just be a case of 'they've got more than me' but the lack of variety is true for certain factions, which can lead to skewed popularity. Extending beyond just ships, certain factions getting lots and lots of bases while others get screwed over, can lead to skewed popularity.
(dont get me started on guard zones, im going to have to say that everyone should recognise that they're all OORP and non canon and black them out).