You're right, and as I skim the release dates of a lot of old DS games I'm realising that the market didn't hang on for as long as I thought it did, but even so, you've sometimes gotta wonder how some of these publishers pick which games they localise and when.
Natsume in particular brings over some really odd stuff sometimes--not just quirky stuff like Umi or the Artdink games or whatever, but ports of Kemco iOS JRPGs and all sorts of unremarkable dreck that no-one seems to care about not even notice. I know smaller publishers can't simply pick and choose what to bring over and that personal relationships count for a lot, but I'm still amazed to see what some of these publishers end up bringing overseas.