I suppose that this is yet another thread to discuss lack of consequence, but have you noticed that the dragon problem actually gets worse after completing the MQ? First you encounter run-of-the-mill, "dragons" that can be taken out by a few town guards, then you are coerced to deal with harder ones as you level up. Often after defeating Alduin.

That would be like if Oblivion left Dremora in the forests after it's MQ was finished.

Any thoughts?

The real reason? An important game mechanic (Shouts) depends on finding and absorbing Dragon Souls, whereas no Oblivion game mechanic depended on Gates continuing to respawn.

But besides that, I actually think it makes some sense that Dragons continue to plague the land after Alduin's demise. I think it's quite possible that he "birthed" many of them out of sight, and we do not encounter them until later.

It could have been done better, certainly, but I do not think it is entirely nonsensical.

Play on master difficulty...lower level dragons are deadly...

Those loyal to Alduin are angry he is gone...so they come seeking revenge.

Supposedly addressed by the 1.9.29.0.8 patch :

- Reduced the instance of random dragon attacks after fast traveling post main quest