That would probably sacrifice the design of the Vita. It would make it bigger and bulkier to add a second set of triggers, probably. I think most games will be fine, with the exception of maybe those that use L2/R2 as their "main" buttons. I'm thinking about shooters here, but I don't know if any PS2 shooters made use of the second triggers. That was an era when square could be a shooting button. It'll probably work itself out -- the PSP didn't have an alternative to L2/R2 either.
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peace comes from within