The foam aesthetics are subjective, IMO foam looks okay if the foam is clean and in good order, and put on straight.
But the sad look droopy issue with old foam, apart from replacements being very expensive, is they are not kiddy proof, a child can easily pull them off to reveal those inviting tweeter buttons, which to a child, are begging to get pressed, and repeatedly pressed quite hard because nothing seems to happen the first six times of getting prodded with a finger.
The issue with fitting grills is if the style look conforms sympathetically to the contours of the sibbles, and if the design conforms to the break between mid and tweeter boxes.
It maybe possible to have all the grill fittings located on the bass/mid driver box only, and the grill extend upwards to cover/protect the tweeter but without touching.
It may also be really smart to have a separate grill for each box, but that would be more intricate in design and style, so presumably more expensive.