That curve ball D:...

I guess you could say the same for what if your bag has a bag, in English.

Die Tasche hat ein Tasche?

Yes, it is

Generally yes, but the one in the jean is mostly called Hosentasche

I wouldn't try looking for reasons... Or you will have to find a reason for Mädchen and Kind to be neuter!

Almost all nouns ending with the letter e are feminine, (Käse is a notable exception)

Ah...but das Gepäck (luggage) is neuter. Best not to get into the "everything in this category is this" mindset.

There usually isn't a reason for most words in most languages.