I know that he's not a senshi (proper), but is there any particular reason that anyone can think of that he doesn't possess more abilities as the series progresses that are reflected through wardrobe upgrades befitting the future king of the Earth?

I have to admit that his Crystal Tokyo garments are rather boring compared to his garments as Prince Endymion. But garments aside, wouldn't that form be better suited to his role to protect Usagi and ChibiUsa? Why doesn't his Golden Crystal activate to restore his sword and grant him greater access to the Earth's power? Perhaps some sort of Holy Blade (perhaps it should have been granted to him? Maybe it should have been his all along?) encrusted with the stones of the Shitennou that assist him in battle? 

I really don't see how his cape is supposed to do so much. He manages to fly, sense imbalances etc., but has a lame attack. :/

I wish he got uprages, that would have been so awesome!

I imagine he didn't receive any because Tuxedo Mask is technically not supposed to exist. He's not a Senshi but he has something similar to a Sailor Crystal.

It's like his past life is accessed through Tuxedo Mask and he was only made to help aid the Sailor Senshi when the enemy woke up. No one imagined there's be more enemies and since he isn't a senshi, that's the extent of his powers until he takes the throne.