What do you mean? STID has an 87% critical ranking on Rotten Tomatoes, exceeded only by TWOK, FC, and the '09 film.
You're using Rotten Tomatoes incorrectly. The rating only means how many critics have a more positive than negative opinion on the film, but it doesn't tell you how much those critics enjoyed the film. A movie could have a score of 100% and have a general consensus of "eh, it's alright". Here are the blurbs for the first three positive reviews from the top critics section.
"Happily, there's a good deal of fun if you like things crashing violently into each other and out of warp-drive at regular intervals."
"The conceptual sci-fi of the original series is nowhere to be found, though you might enjoy watching the skinny young actors approximate their counterparts from the 60s; Chris Pine is especially good as Captain Kirk."
"While the action is often electric, it's the relationships that matter. That, and a lippy regard for a cultural legacy."
All three of these reviews are positive, but two of them aren't exactly glowing reviews.