He brought the people into the land of Yisroel, conquered their enemies, what more could you ask for?
I heard that if Moshe had been permitted to go into the land, he would've been Moshiach, but why not Yehoshua???
the answer is simple (according to Rambam's rulings on Moshiach here)
Moshiach is one who fulfills the following in this order:
Brings all Jews to the promised land (check)
Fights and wins Amolek (nope)
Builds the Temple (nope)
Doesn't die before completing the list (fail).
So 1 out of 4 - he's not the Moshiach. Please read the link, it's not so long.
Could Moses be the Moshiach:
It is widely accepted that if Moses would enter the Land of Israel he would eventually COMPLETE THE WHOLE LIST and be the Moshiach, not just because of entering the Land alone as you suggested. Therefore Yehoshua cannot be considered a Moshiach by entering the Promised Land alone.