The reason why Rotom-Appliance is not OU is that some players used a team containing all Rotom forms. This would make Rotom have 6 usages in one match, which is clearly not what we want. Until the server has in place something that disallows you from using more than Pokemon form in one team (be it Rotom, Deoxys, Giratina, Shaymin or what have you), we can't count Rotom usages correctly.
However, Doug said that he'll implement this clause on the server in the very near future.
Won't this have implications on the UU Metagame for the time being?
Sorry, that was brief, I'll update it.
Basically, although we can't prove it data-wise, if Rotom is being used often in OU (which anyone can vouch for), then it would obviously be an overly-powerful threat in UU. As for the incorrect count, due to the use of several Rotom forms, we can assume that,
if these teams are leading with Rotom, then we can use the number of Rotom leads (
2372).
For each Rotom lead, we can just assume for this example, that they would be a Rotom-Team. Excluding the original Rotom, there is five Rotom-X's. Basically, in these cases, 4 usages should be eliminated to give Rotom 1 use in these teams. So, 4 times the lead-count can be subtracted from the total (
17689) to eliminate the extra usages all-rotom teams.
2372 * 4 = 9488
12689 - 9488 = 8201
So, we have a
worst-case scenario of
8201 "clean" Rotom-X usages. Considering the Quota for
OU was
8654, then we have a gap of
453. This is assuming that all Rotom leads are followed with 4 other Rotoms, which is not true in every case (I have seen a team with a Rotom lead, 2 other forms and 3 normal pokemon.), as teams may have anywhere between 5 and 1 Rotom-Xs.
Regardless,
8201 is, in my opinion, more than enough to get it into BL, at least.