I think the biggest thing hurting the SCCA is not having a PDX program on the race weekends, though I would like to say that I feel this is the BIGGEST benefit to racers running with the SCCA also and the thing I like the most.
The problem is most people start out in HPDE with NASA (at least on the West Coast) and then they make friends there and don't want to switch even though you get longer races and more track time with the SCCA.
I would not like to see SCCA add PDX to the racing weekends, but I WOULD like to see them add one Time Trail group to each race weekend with NASA like rules (i.e. passing). This would serve as a good steeping stone for racers but would not change the all racer atmosphere that SCCA weekends have, that I really like. Where NASA makes you feel like you are just there to fill in the spots they could not with HPDE people.
The thing that really bugs me about NASA weekends is once I started racing I payed more, got less track time, and a raced on a WAY more crowded track then the HPDE people, When you are just starting racing track time is still really important to you at one time I was getting 25% less time then the HPDE people.
I will say as well that I think the Regional/National thing is really silly and should go away. A lot of people (including me) like that every class in NASA is available for a national championship.
Oh course is does really suck that you cannot work your way up from beginner to racer with the SCCA since I don't feel like the 3 day school is enough track time for people to go out racing. You almost have to go get other track time with other organizations and I think most people just stay with the group they start with.
Just my 2 cents.
Disclaimer: This is all based off what I have seen in the NASA NorCal and San Franciso Region SCCA only so may not reflect each group as a whole.