I was writing my first game in XNA .NET framework, and I'm really glad I had that experience. It forced me to understand (and figure out) the insides of a game engine, such as collisions, GameObject model or game loop really well, and since by that time I had no idea something like game engines exist, I learned to not take those features for granted and actually had to research and write them.

When Unity went free, I appreciated the features so much more, and now I also see that some of the newer developers have no idea what's actually happening in the background, which is a shame.

I'd recommend that anyone interested in gamedev starts more low-level, and only after that gets to more heavyweight engines. Sure, you probably won't make a 3D game, but making a simple platformer from scratch is an amazing learning experience.