Nobody suggested that they should have had the game in development for Switch earlier. What I said was that they clearly weren't actually going to consider porting the game to the Switch, because if they thought the game would be worth porting to the Switch, they would have already started considering it. Their choice of language gives away the truth.
If they were considering porting it to the Switch, but had decided to wait to see how Dragon's Dogma did, they would have said that they would port it if Dragon's Dogma did well. They said they [i]might[i] consider it if Dragon's Dogma did well.
And as you point out, the longer the leave it the less it would be worth doing. So if they were being honest about their intention, they would not only have considered releasing it on the Switch, they'd have done some initial work on it so that it can be ready more quickly.
I have no problem, inherently, with a company deciding they want to see how another of their games goes first, before committing to developing or porting a particular game. I have a problem with dishonest developers using the passions of fans to boost sales of another title by implying they'll release a game that they have no intention of releasing on that system.
It's not the first time that they've done it. Remember on the Wii, when they ported Resident Evil 4 (from the GameCube, which means it didn't require much work), and said that if it does well, they'd support the Wii with more content like it? RE4 did well (as in, sold better than GC and comparable to PS2 - not bad for a port of a game from 2 years earlier), and the Wii got "Resident Evil: Umbrella Chronicles" with a similar promise ("more support if this does well")... it sold well for a spinoff... and Capcom just made more ports of old RE games and another spinoff like Umbrella Chronicles. Meanwhile, Resident Evil 5 was released for PS3 and 360. The truth is, they never intended to make good on their promise of more real support.
And the same is true here. They have no intention of releasing DMC5 for Switch, whatsoever. If Dragon's Dogma does well, they'll find an excuse not to follow through.