Say that to Hideki Kamiya and DMC 1:
The game that made DMC what it is, story and gameplay.
After DMC 1 , DMC became exactly what you say : shallow, fun, good time and nothing else.
But before Hideki left DMC had a good story foundation gameplay.
So you NEVER know the plans Hideki or his coworkers who worked with him on the story had for Devil May Cry.
What makes you think they had any plans? They might as well have just made Devil May Cry to be a single, stand-alone game without any plans for sequals. And maybe that's why he wasn't on the team who made DMC2.