my 5.5 yo still has one left that she uses regularly. i would rather that then milk spilled on my couch or carpet. there are only hard floors in two rooms, the kitchen and bathrooms. the dining table is over carpet. we have had numerous spills on the table that ended on the floor. she drinks out of a regular cup at mealtime. if she is going to be running around the house playing, she gets the cup with a top. i don't think its a big deal.
: let me know when you get to this age and if you still think the same.
also, my almost 9yo will occasionally take a cup upstairs with him with water in it. he will take a cup with a top. i think i still have one of the toss ones. i'd rather that then him dumping it on his bed. they usually only take water to bed when they aren't feeling well. also, we have 4 cats who would drink out of the cup if it didn't have a top in the middle of the night