Green creatures and spells can generate life points and mana, and can also gain massive strength through spells
There are literally volumes that could be (and have been) written about what constitutes an efficient creature in Limited and how highly you should pick certain cards over others
The sticker's shape becomes a problem when it looks like the sticker has been tampered with or scraped off in some way
Uril is so nasty with a trample granting Aura like Rancor or a flying Aura in White, or unblockable Equipment like Prowler's Helm
Notably, Alandras abilities happen each turn, not just during your turn, so drawing multiple cards on an opponents turn, such as with Thirst for Discovery, can be an effective strategy
With Gwendlyn, the issue was likely more the art than the card itself, which has been known for being fairly racy by Magic standards