Never played on the tv tables though I did hit a few balls on a riley table that was used for the Canadian Championships one year, it was ridiculously tight. So much so that the high break of the tournament was a 115, no one else broke the 100 mark including Alain Robidoux. I watched Alain warm up for a match and he never broke 30. So I doubt it was indicative of what is played on television.
The theory behind it is that they need to provide a true test for professionals. This is similar in Golf, especially in the majors, where they play on tougher courses. The difference is that the difficulty of a golf course is more apparent to the viewer than that of a table. Especially snooker and pool since if your not looking hard enough, or don't know what to look for, then all pockets look the same.
That said if your going to play on tables with brand new cloth and rails you need to tighten the pockets in my opinion because they play much larger when they are new. People have been saying for years that the pro's play on big pockets, and based on some of the balls that drop it does seem like it from time to time. However that has more to do with condition of the table, and I believe they change the cloth on the t.v. tables twice throughout a tournament.
