This was yet another card restricted in 1994 during the time when Wizards of the Coast were just beginning to figure out how best to adjust their game
A well-balanced curve is also essential so that you can pull bigger and better things out of your deck
They never know if you have bloodrush when you send it into a bigger guy, and a lot of the red decks really like having a little guy to get the beats going
Tezzeret the Seeker flies in the face of one of the guiding principles for planeswalker design: they must work well in any deck against any opponents deck. While we would see a much more linear design in Nissa Revane the following year, Tezzeret was the first niche planeswalker design
If you pay one white mana, tap the card, and exert Pride Sovereign, it can even make two 1/1 Cat tokens all by itself
The fact that you can play the exiled cards as long as you control Lightning is a nice bonus, but the lack of Haste here really kills the card, in my opinion