Why don't all plants grow like weeds?
every advantage has a disadvantage.
self seeding means less genetic diversity, fast growing also means more energy requirements  and even a structurally weaker plant, fast reproducing means tiny sieeds so individual seeds have a very small chance of survival. Biology is all about cost vs benefit, there is no such thing as universal advantage.
regrowing is actually something all plants can do provided they have enough resources, this is one way humans replicate crops. Weeds are often more sensitive to ground conditions, and don't do well in places where humans have not cleared and irrigated the land. weeds are often pioneer species good at taking over open land, one effective way to deal with weeds is to plant a cover crop because weeds can't actually compete well when there is already healthy grass. Many crops on the otherhand are being grown in sub-optimal conditions, in climate/soil other than the the one they evolved for while weeds tend to be native plants already adapted for the local conditions.