It's odd that Nintendo's success tends to have unintended consequences with third party support. The Wii was an unprecedented success and third parties decided to take advantage of that by flooding the library with shovelware. Now the Switch is a huge hit and third parties are aggressively supporting it but we get nickel and dimed all the time like we're seeing here. It's the infamous "Switch Tax". For some reason third parties see a high selling Nintendo console as something to cheaply exploit rather than just support in a "normal" fashion like they do the other platforms.
Does Capcom think that there is much demand for a standalone port of DMC1? The general reputation seems to be that the third game is the high watermark for the original trilogy so I don't think there is any special interest specifically in the first title. DMC2, meanwhile, is generally considered to be a bust so if the intention is to eventually sell all three individually I figure the sales for that one will be quite poor. Packing them as a trilogy seems like the ideal way to sell those games these days, which is exactly what Capcom has done until now.