Absolutely. TOS focused heavily on Kirk, Spock and McCoy, to the point that every ep focused on one of them, and even McCoy was secondary to Kirk and Spock.
All the other shows gave attention every now and then to every member of the main cast, which I think made for a stronger show with better developed casts.
But I can't deny Seven did dominate the series once she came on. She was popular, and there were a lot of great interesting stories around her, but she did become a quick fix to all their problems.