I personally was into trophy hunting on games that I really enjoyed playing but about a year ago after I reached 100 platinums something changed I semi switched to PC gaming and lost interest in trophy hunting as my backlog was growing and the amount of time I had each week to play games was diminishing quite a lot. Which is probably the reason why I hardly used this site much in the past 18 months or so.
I feel that I can probably get back into it if I really tried and I do intend to come back and finish as much as I can of the games in my backlog but I honestly don't know how long that will last. But I do have a list of about 4 or 5 games that I definitely want to finish pretty much guaranteed.
So to put it simply do it because you enjoy it I don't think completing games to 100% so your profile looks top tier is an incentive (well at least not for me anyway) or a goal.