The reasoning behind this is because they were good items, just because they costed tix to begin with doesn't mean they should be non-purchasable in the catalog for robux now.
Not ALL of them obviously but i'd like to see some brought back.
For example: https://www.roblox.com/catalog/1081366/Astronaut-Helmet
^ Was converted from tix to robux why not some of the others?
<3 https://www.roblox.com/catalog/21754986/Cowl