hmcpretender: I disagree to you diagreeing. Equiping the best-in-slot-weapon for any given situation is exactly one of this non-choices I was talking about. A simple script could do this just as good if not better than the player and therefore it doesn't add anything to the gameplay (other than superfluous micro management).
That assumes there is a best-in-slot weapon for any given situation. Sometimes, weapons (or other equipment) have various special effects, and which one is best may be influenced by the player's strategy. Consider, for example, that there often isn't a "best" spell in games that have magic, and sometimes there are trade-offs to be made.
Perhaps a more interesting example might be accessories. For instance, in Final Fantasy 6, which accessory is better for Strago: The Earring (which boosts the power of spells by 25%) or the Muscle Belt (which boost maximum HP by 50%, and keep in mind that there are a few Lore abilities (Pearl/White Wind being the one that occurs to me first) that are affected by HP and work better for characters with higher max HP). See how the choice isn't clear cut?
hmcpretender: Last but not least a skill system might prevent you from swichting your weapons at will as your character might not be proficient with all of them.
I consider weapon proficiencies to be one of the worst examples of skills. In most games, there isn't any strategic difference between weapon types that is obvious before one is aware of what weapons there are to find; hence, I consider asking a player to choose a specific weapon type at the start of the game to be bad game design. The Infinity Engine games, for example, suffer from this issue. (Things get more interesting if the game actually makes the weapon types strategically different throughout the game and accurately informs the player; Lords of Xulima is an example that does this well, though I happen to dislike the skill system in that game as it made me dread leveling up.)