However, I'd just like to turn it around for the purpose of this discussion. Is a fighter who, on every round of a combat, is able to Trip someone (with a high degree of success) just as worthy of breaking your Suspension of Disbelief?
No. I agree with Pawsplay -- a fighter with a specialized attack in real life is most likely to use it over and over as long as it's working. It's up to the opponent to actively come up with a counter, if any.
Admittedly if you're doing comic-book or movie-style fighting, then you're likely to see a special attack only 1-3 times within a given story. But that isn't a "suspension of disbelief" issue, that's an "I like my fights cinematic" issue, if you so prefer. Personally I do prefer my D&D games without this particular added barrier to suspension of disbelief.