One convenient thing about TOS is that everything was done optically and the prints that were scanned for broadcast were still available. They were able to go

One convenient thing about TOS is that everything was done optically and the prints that were scanned for broadcast were still available. They were able to go back to the film without being forced to redo all the editing and effects, as was necessary for TNG, which was composited and edited on tape. As you say, they were wise to include the unaltered versions on the Bluray releases. The "upgraded" effects are certainly interesting, but far from subtle! If you want to see the unaltered version of TNG you are forced to go back to the DVD's. Fortunately, the restorers were meticulous in recreating the original special effects as faithfully to the original as possible, even to the point of bringing in a lot of the people who originally did those effects in the 80's and 90's. Practically nothing sticks out as being as out of place as the upgraded effects that were done for TOS do. Even though a lot of what we see in the HD release of TNG is entirely new, it blends in seamlessly. Extremely impressive work! TV of the late 80's and 90's seems destined to be a bit of low-resolution dip for for the foreseeable future. The TNG restoration was expensive and CBS Paramount hasn't yet gone forth with restoring Deep Space Nine. It may simply be too expensive to give most shows the same treatment. An added problem of the late 90's was the advent of extensive use of CG effects in television. DS9's restoration will be complicated by this, and another great example is Babylon 5. The models, animation files, etc. for this show's CG effects were lost, so they'd need to be recreated from scratch if the show was ever to be restored in hidef. Even the DVD releases suffer from poor quality due to this.