Base models are given 'cult' status without any justification - why?
Because, unlike some other bigger manufacturers, their base models were excellent mountain bikes too (they didn't reach quite so far down the price ladder as some, which helped.) The frames were better than the components hung on them (i.e. well worth upgrading when the first drivetrain etc wore out) and they were great value for money.
Justification enough for me
The reality is that the Lava Dome was the ultimate upgradeable frame - they didn't cost much, their owners always loved them and there must be a reason why. Somehow it's always been cool to upgrade a Lava Dome in a way that say a Rockhopper or a Muirwoods just wasn't considered worthy of.
It may not be logical, but why do men love beautiful women? Maybe there's not much logic in that either, but we do.