Firstly only the finals are 15 rounds, most matches are 5 rounds maximum and take 10-15 minutes to complete. The finals last year took 20-30 minutes.
I agree that having a category of 181-210 might attract more players in that class, but it still probably wouldn't be many and I'd be struggling to get anyone in the higher classes.
The results from the health poll I did (not an exact science of course but a good indication) suggest that only 2% of players have 211-249 Health, and 2.4% have more than 250. Applying to those percentages to the total number of entrants would suggest that even if a representative proportion of the population entered the higher classes, I would get 2-3 people in each of your higher classes. My experience suggests that proportionally less people at the higher levels enter events like this, so in reality that would likely be reduced.
In the 2008 Middleweight class (151-200) we had 4 entrants. In Heavyweight (200+) we had 4 entrants. Now this year we have 4 entrants in the Heavyweight class.
The Middleweight class this time has expanded because there are a lot more people over 150 these days, but at higher levels that expansion does not exist, or is minimal.
So while further class divisions might level the playing field in the higher classes, I don't see where the entrants are supposed to come from.
I think in this thread we've had 2 people say that they would have entered if there had been a Super-Heavyweight class or similar. They didn't enter because Star was too tough, and now still haven't entered after Star withdrew, so make what you will of that.
Of course there may be others in the same position who haven't posted about it.
I would love to have more high-level players enter the tournament, but the fact is that the numbers just don't add up, and there seems to be a distinct lack of interest from that part of the playing population.
Frankly I'm more interested in running a good contest for the 150 people who have entered than worrying about the 2 people who didn't.
