Recently caught a You Tube clip of the old 60's-70's Concentration, and one sound transported me back to the day, the kachunk-whirr-kachunk of the motors and relays that turned each of the board panels around. Couldn't help noticing the original board contained 30 panels (5 rows of 6 across) while the later, hi-tech board of the revival version had only 25 (5 rows of 5.) Did they have to "dumb down" the board to suit the contestants or the audience?
Yep, you caught on to the Alex Trebek "Classic" revision from 1987 to 1993. Remember that "Concentration" was in its first NBC run from 1958 to 1973 a low-tech affair, with no CGI or any electronic imagery. The pieces of the board were termed "trilons," with three panels, one of which showed the number (1-30), the second showed the prize, and the third the piece of the rebus puzzle. There are legends circulated by people such as then-producer Norman Blumenthal about the frequent mechanical malfunctioning of the rotors, which would be expected from the constant and repetitive use during a game, particularly if one or both contestants called the same number many times within a short period. When NBC cancelled the game in March '73 and leased it to Goodson-Todman to be revived that fall with Jack Narz at the helm out in El Lay, believe it or not, the game board and the prize panels behind the contestants were actually shipped out west, rather than the designers building new ones. I always thought that was very strange, but apparently it was a condition NBC placed upon the G-T production. But around '75 or so (and I don't know for certain the details), apparently one (or more) of the trilons caught fire or spewed smoke during a taping, and the set people had to, indeed, rebuild the board. I think difficulties like that were the main reason that other NYC shows like "Jeopardy!" used the old standby pull cards, but "Pyramid," which premiered right after the NBC "Concentration" cancellation, used automated trilons effectively for the next several years.
Now on to your main question, it was, of course, a given that G-T would use CGI when it decided to revamp "Concentration" in the mid-Eighties, first on the unsuccessful 1985 pilot with Orson Bean. Personally, I thought G-T cut the number of pieces down to 25 mainly to try to speed up the game. Remember that the NBC original had games straddling episodes, so players could take all the time they needed. That changed, though, with the 1973-78 revival, since it was syndicated in the days before satellite delivery and episodes were "bicycled" among stations. That and the fact that some markets only aired it weekly as part of the Prime Time Access Rule evening "checkerboard" mandated that shows had to be self-contained, with no returning champions (such as "Wheel of Fortune" is today). I remember that on the Narz version, play was usually interrupted with about 9-10 minutes left in the program to go to a sequential reveal, with the first player to buzz in correctly winning that game and possibly going on to the "Double Play" bonus game. The Trebek version was under similar time constraints, but, according to Wikipedia, actually had straddling and self-contained play at different times during the run. I do not think in any case that making the game easier for the contestants had much to do with the decision to reduce the number of pieces to 25--it was about saving time (and money by cutting down on two or more prizes that would have been available on the earlier versions) and keeping a faster pace to generate excitement. That is to say that the patience of our grandmothers' generation (who watched the NBC original) was dwindling, since people by then had remote controls. These days, forget about it.