Yep. In fact there's arguably been a bit of tension in Battlefleet Gothic between fluff and game balance (e.g. Space Marine and Ork fleets being a bit underpowered or unwieldy on the tabletop versus other ships for fluff reasons, while Necrons were very powerful because they were The New And Ultimate Villains of 3rd ed
40K). Over the years the game slowly trended toward emphasising balance, e.g. giving Marine ships more loadout options.
Here's a quote I found in an old White Dwarf that seems relevant. It's not about
40K--instead it's from a retrospective article about Warhammer Fantasy,looking back from 7th edition--but the point still applies:
Jervis Johnson: "It's interesting because in the early days the miniatures informed the game's development and background. So you would have things like the Goblin Fanatics [looney Goblins who swing huge balls-and-chains] being created, not to any brief, but by a sculptor just appearing with them one day. Nowadays [circa 7th edition Fantasy / I think 5th ed
40K], it is very much the other way round; the background is established and this informs the models we require from the sculptors."
Of course that's not the whole story. A lot of things are shoehorned into the background because 'we need a new kit to sell', or (especially from the late 2000s onward) 'we need a really big, impressive
CAD-designed kit to sell'.
One amusing instance of this occurred when the reasonably proportioned 2nd ed metal Catachans were replaced by the roid-rage 3rd ed plastic ones. The new
IG codex dutifully described Catachan as a high-gravity planet, and said that its people were referred to by other Guardsmen as 'baby Ogryns'.
I'm also sure that despite Jervis's words, the sculptors themselves continued to come up with crazy models they liked and the game designers accommodated them somehow. Sometimes people blame marketing when really a sculptor just wanted to let their creative side loose.
From a game design perspective, sweeping rules changes like the transition from 2nd to 3rd ed
40K also caused a bit of a snarl when models intended for one edition didn't really work in the new system (like Swooping Hawks and Warp Spiders).
There's also the hobby aspect to consider. As much as people mock the 1000-marines-to-a-chapter thing, I suspect part of the reasoning behind that ridiculously small number is miniatures collecting. A hobbyist in the 80s or 90s could *just about* imagine collecting and painting an entire chapter of 1000 marines. Some actually did. For most it was an impractical dream--but one that felt theoretically achievable. I don't think many people would have even bothered to try if the number had been 10 000 or a million or something more sensible.
One thing I really appreciate about
BFG's fluff from a hobby perspective: ship numbers. Considering the sheer size of the galaxy, the number of capital ships in a typical sector fleet seem far too small. But it makes collecting a complete fleet achievable. Or at least it did back when the models were available. I was amazed when I read the description of the Damocles Gulf Crusade in the 3rd ed
40K Tau codex (one of my favourites from that era) and realised that I had nearly enough Imperial ships painted up to play out that campaign on the tabletop, battle by battle.