If the false memories are constrained to sentiment, then I think it could be alright. I’ve become quite disillusioned with many things over the years; this disillusionment only serves to bum me out. If I could rewrite some of the few pivotal experiences that have me feeling this way, I would immediately benefit: I’d have more fulfillment in what I do and my disposition would benefit from looking forward to things as I used to.

On the other hand, one could imagine expunging useful negative feedback and being worse off (e.g. less socially adapted, lacking in character, etc).