Learn Finnish: Miksi te ette halua tulla sisään?

Haluta is a Type 4 verb (ending in -ta). To make the negative form for Type 4 verbs, you take the dictionary form, drop the final -ta or -tä, and add an extra -a or -ä. So, haluta drops the -ta and adds an -a to become the stem halua-. The negative word ette (you don't) is simply followed by this stem: ette halua.

Why is tulla (to come) in its basic dictionary form here?

When you have two verbs together expressing a combined idea like "want to come", the second verb always stays in its basic dictionary form. This rule remains exactly the same in negative sentences. Since the first verb is already conjugated in the negative (ette halua), the second verb tulla doesn't need to change.

Could I just say Miksi ette halua... and leave out the word te?

Yes! In Finnish, the negative verb ette already tells us who is doing the action (you, plural or formal). So, the pronoun te is optional. Including it just puts a little more emphasis on the word "you".

Why do we use sisään (into) instead of sisällä (inside)?