Well regarding this, I suppose main reason to remove low lvl items is to save space both in terms of points and items in overall, there will be a lot more items in shop and most of them will cost way less coins than those under 200 lvl items, it's really hard to say what would be fair, there are other items which are not planned to be reintroduced including enchants and so on, which also is not ideal and places those who did not get them into disadvantage including lvl 80s, as far as I know existing items will not me removed.
I really think there is no reason to hold on market any items which can be obtained in game, which hopefully will be case for most of them soon enough. Here would be nice to put at least top lvl item sets for twinks, but then again, getting entire set for twink sounds like easy way to gear up... There's still hope that new realm will fix long lasting issues.
What I see here is that warmane is getting rid of old system which was based on different goals, right now they are putting in something new, I'm sure not everyone will like it at the end and I'm quite afraid this is already devs nightmare.