You know what opinions are like...everyone's got one!
I don't see how this will hurt multihull sailors either - it will probably be good in the long run. The exposure that the monster tri has already given us is good...everyone generally considers it "the ultimate speed machine" and is in awe of it (how could you not be!). There have been plenty of 90' monohulls - but no multihull (to my knowledge) has ever been built this large with closed course racing in mind.
On the other hand, once this is over (and hopefully we'll see teams that are more willing to negotiate agreeable events in the future), I'm sure it will be back to the usually tightly controlled monohull racing with small (and expensive) technical gains made inside the rules. I do think it would be exciting to see an open box rule America's Cup for a series of multihulls similar to a scaled up A-cat rule (that would permit tris or cats) where the rules literally fit on one page. THAT would be neat to see what comes out of it. Keep the cost low by limiting length to 30 or 40' but let the designers and sailors have some fun learning how to go fast....really fast.