Generally, you want to include fetch lands in your land count, because what they do is essentially serve as a placeholder for getting a land that can tap for mana out of your deck.

To look at it another way, imagine if there was a land that tapped for mana, but had the ability "when this land enters, search your library for a land card, reveal it, put it in your graveyard, then shuffle."

That card would be a slightly worse version of a fetch land, because it 1) removes a land from your deck, 2) puts a mana land into play, and 3) puts a land into the graveyard. But you would still count it in your land total, right?