I don't see where it's extremely exclusive. Everyone had the same opportunity to experience 503 Service Unavailable errors as anyone else. The brewer has to make a decision if it's important enough to take time off from work, shift their lunch hour, or call in sick to be available for the opening of registration. Moving it to a Saturday or evening may work, but not everyone is working banker's hours, (2nd & 3rd shifts, working weekends, etc ), so you potentially exclude them.
I am against a prequalifier for the ability to enter the first round of the NHC. That's potentially 3 brewing days for one competition depending on the style. Now you exclude the people who try to fit a brewday in between work, kid's karate, family time, and all the other crap we save up for the weekend.
I enjoy enter the national competition, but the rule changes proposed will exclude me from entering in the future (prequalifier, $30 entry fee, etc.)...so mission accomplished I guess.
I don't see an too much of an issue with lowering the limit to 10, but I would never enter that many anyway, so I'd hate to exclude the one who do.