It's a little bit stupid but ...
If you drop theses mounts with the 1% droprates, and then, someone looks at your achievements, and can see that you never did LK25HM or YS25HM in time, couldn't it be a shame ?
I mean
"Ah ah, this guy have the mount but never accomplished the achievement in time ! Naab lulz uninstall !"
That's what could this someone think...
Or maybe i'm simply paranoid ?