As for the 25 v 50 thing, we just don't have very many 50m pools here and even fewer that will let us train or compete in them. Saying that we can't set records here because of our pool situation puts us under even more strain. As it stands, records here cost so much more because of our isolation and the cost of getting international judges over. Do we really want to disadvantage people that way or to create even more records? What about fresh and salt water records? We used to have those. With and without suit? Bifins and stereo fins? All of a sudden we have 40 world records and potentially as many people claiming to be the world's best. I'd prefer to see it reduced, not increased.
You could say most of those things about competitive swimming too. Or finswimming.
Also, there aren't that many 50m pools in Finland either, closest is around 100km away from where I live. I haven't ever had a change to regularly train in a 50m pool.
And if I'm not completely mistaken, I have already seen videos of Dave set a DYN WR in 50m pool in NZ and DNF WR in 25m pool in NZ. How does it become more difficult to organize if he does them the other way around?
Almost everyone is using good monofins and suits, so currently there is not much need to start own disciplines here.
However, I'm not against separating bifins and monofins to their own disciplines, as is the case in finswimming, but it would have a different effect on competitions than separating 25m and 50m pools. It would add more disciplines to every competition, since now there would be four disciplines to do, regardless of the pool. Usually the competitions are one or two days long, so it would be hard if you wanted to do static, dynamic without fins, dynamic with monofin and dynamic with bifins.
With 25m and 50m pool rankings, there would still be only three disciplines per every normal pool comp.
With fresh and salt water records, well, I'm not against it. At the moment I'm not very much for it either. There are not so many good and deep fresh water spots, so breaking, for example, the fresh water CNF record would become hugely just about finding the best place to do it. In a sense, this is already the case with all depth disciplines, but fresh water ranking would greatly amplify the problem.
With 25m and 50m pools this is not a problem, since both of those pools are common (enough) and there are lots of competitions held in both of these pools. Also different pools are quite similar to each other.
I don't really see why having more world record disciplines would diminish their value. Having the 50m breaststroke WR in short course would be just as impressive to me, whether 1500m freestyle in long course was a discipline or not. Or if the value did actually diminish, maybe we should drop DNF as a discipline, since there is only around 10-20% difference in the results between DYN and DNF anyway. Same with CWT and CNF. Also what the heck is this FIM thing, it doesn't make any sense to me. And so on, until we don't have any more disciplines left, since they diminish the value of other sports' world records.
As I see it, separating 25m and 50m pool rankings could somewhat increase the popularity of pool competitions, that have 50m pool DNF or 25m pool DYN, by motivating the athletes to compete in different kind of pools. For the downsides, I don't see any.