Well it does seem to create significantly larger screenshots. I suppose with the proper screen, it would be a lot like seeing a film in a theater. But do you really want to notice every imperfection or detail in the sets, clothing, makeup, and possible booger in the nostril that was never meant to be seen?
A. The screenshots are larger to you when you view them up close on a PC. From a normal seating distance on an HDTV the episodes look great.
B. In addition to the above, it's a rather silly thought to say suddenly in HD you see everything you weren't supposed to. TOS was not such a cheap production that you ever saw tons of errors and makeup lines, etc. Further, remember this was shot and edited on 35mm film, the production staff and editors all saw TOS in pristine condition at one point in the '60s, which would have looked much like the Blu-ray versions, and it got their approval.
C. So what if you see the occasional latex appliance seam? We all know they are there, it was a TV show on a tight budget in the '60s. It doesn't detract from the generally amazing detail and rich color palette that's been there on the 35mm film this whole time, that a proper 1080p restoration has now made it available to home users.