The product on the pitch has to be considered as a contributory factor, though.
I imagine any Wasps fan who made it to the game on Saturday would be considering the wisdom of doing it again, so poor were we. An upturn in performance - just doing the bloody basics right - will draw in more "casual fans" who won't necessarily turn up week in, week out regardless.
Also, I know it goes against all financial sense, and the salary cap is a blocker, but a big name signing puts bums on seats. A Radradra, a Piutau, a Genge...
The atmosphere will never be great in a stadium which, when all is said and done, is too big for a Prem Rugby club.