Hmm, there's a little bit of right, and a bit of wrong in this in my view. No doubt you're right that a lot is the spectacle and the occasion.
Disagree about the history of clubs however. It doesn't for the one-off, but the club will have uber-fickle fans without the legacy of a sense of place that comes with time. The trick for any newly arrived club is to keep themselves afloat as they try to embed themselves, so that becomes less important.
As it stands, a large high profile start is not surprising for Wasps really. As you say, some will be attracted by the occasion, by curiosity, by whatever. Those people however are also more likely to be attracted by other leisure events on offer elsewhere, so they're more likely to bog off. One thing CCFC does have in its favour is a hardcore of embedded fans who are there because of tradition, the past and the like - Wasps doesn't have them.
The genuinely interesting objective POV is more why someone wouldn't have bought Cov Rugby and spunked a load of money at them to build them up to the Wasps level. In terms of the long term that would have had a better chance of succeeding in my view. In terms of the short term probably not, because there wouldn't have been that curiosity value and the sense of exposure (I'm guessing Wasps also want to piggy-back on the World Cup - so maybe we need to cheer on Wales, Australia... and Uruguay?)
How it plays out over the next 5-10 years will, objectively, be quite interesting.
But yeah, there's already a senior rugby team with a tradition in the city, not to mention Rugby Lions close by so hell, go and watch them if you love your rugby.