The Crimson Binome
Hero
There's always a chance of death. You might try to spider climb up a wall, only to find that there's an anti-magic field up there. Or the wizard could lose concentration somehow. Or. Or. Or.Now the wizard could just cast a level 1 or 2 spell (jump, spider climb, misty step, levitate, or tensers disk can bypass most STR based hazards just fine) and have no chance of death. So in this scenario, it is better for the wizard to use one of his low level slots. Especially given that at levels 5+, a cantrip will tend to do about as much damage as a level 1 spell. By level 5+, the wizard should easily be capable of preparing at least 2 exploration utility spells.
There's also a substantial period of time where level 2 is the highest spell level you can cast. And the more powerful you get, as level 2 spells become a trivial resource, the more likely you are to encounter magical counter-measures. If a difficult obstacle can be bypassed easily with a low-level spell, then there's a good chance that the opposing force has already taken that into consideration.