{{temp|t-SOP}}

There is no immediate rush to delete them as they all use the same module anyway, and the only difference is the interwiki parameter. Essentially, your proposal means to transfer the interwiki parameter from the three templates into all the entries. We could do that, but we'd have to add that parameter and convert all translations, which could take a long time. The current situation is ok.

We could get rid of {{tø}} because the module is able to detect (to what accuracy I don't know) which languages can have valid interwikis. That would leave {{t}}, {{t+}} and {{t-}}. Personally, I would like to merge them all into {{t}}, and abandon the practice of changing the display of interwikis depending on whether the foreign Wiktionary has an entry. It's not really a huge usability issue (how many people even use those links anyway?) and we need bots to constantly update {{t}} into either {{t+}} or {{t-}}, which just isn't being done and will probably never be done.