If the tournament pays for a player to attend, they should mingle with non pro players as part of the event "sponsoring" them. Makes for a great experience and encourages players to come out and maybe have a chance to see the greats.
If a team sends them out then maybe practice rooms are a good idea, but friendlies and pools are good practice too. A hotel / space nearby to relax is of course a great way to make sure top talent is encouraged to come out.
The problem is when it swings too far one way or another. Stories of random players messing with pros, trying to hurt their hands, swarming them so they can't make it to their matches, etc. That can be stressful for players, and then you have pools on top of that. Pro players are used to tournaments but still that's why I understand why they would like some privacy.
LCS does this rather well, you can't meet / see players before the games, but after each set of games, there's about an hour of photo / talk time with the players. The area is staffed heavily so nothing bad happens to the players, and people get to see the pros they idolize. A friend of mine just about died happy getting to take a selfie with Bjergsen.
Also I feel no player should be floated, regardless of skill. Seeded higher in bracket yeah, but not floated out of pools or anything like that. If a player is truly pro they should have no problems consistently making it out of pools. I know a lot of pros dislike the tournament wait times that come from progressing in winner's bracket, but so do the rest of us.
That's where invitational like Smash Summit come in - they're invite only, exclusive to pro players, and are more relaxed as a result. If Nintendo did a Capcom Cup style circuit that would be great. EVO had a back room where players could prep, and that's great but not every major has the space / budget to do that. Hell most biweekly tournaments are run for 1-200$ and get by on the skin of their teeth. Smash has always been grassroots up until a few years ago, which is crazy to think about.
Hell you could even advertise a VIP lounge where top players get in for free and other tournament attendees / spectators could pay out the butto be in the same area. ESL One Frankfurt does this and it seems like a success and a good revenue source as well as a place for pros to "get away" from most of the public but still meet and greet with the more dedicated fans.
There's a lot of growing pains to the whole E-sports level of attention Smash is getting. There are a lot of ways it can go, and it'll be interesting to see how the VIP room talk is handled. It can be good for both TOs and Pros, but it can easily swing to benefit one side more than the other and leave the other unsatisfied.