This isn't a reasonable position in 5E, which has a truly pathetic equipment and clothing section. Do you have a better list for your table?
It is absolutely reasonable. I'll repeat for emphasis and clarity...
As I said, this is how the game of D&D is played and always has been. Others may choose to play it differently and I have no problem with that. But MY understanding of how the game works is definitely stated to players at the outset, written down for them to see (whether they actually DO read it or not) and still verbally repeated as often as is necessary. If a player sees inadequate description for gear - they are free to SPECIFY their gear, to have their PC buy something NOT listed or better described by default, and list it in their character sheet. I cannot reasonably ASSUME that anything they come up with on the fly is something I SHOULD HAVE KNOWN, any more than things that I DON'T SAY as DM is something THEY SHOULD HAVE KNOWN.
Even though as a DM I specifically
dislike and avoid playing Simon Says and Gotcha! games as a valid approach to D&D, I will only give so much leeway before a ruling must be made. Players must
be clear and specific if the ultimate safety of their PC's is truly important to them. That is THEIR responsibility as players to safeguard their characters, not MINE as DM to protect them from their own poor play by being vague, being blind to hints, and not taking advantage of opportunities SPECIFICALLY given in situations like this. As the OP noted, the player wasn't forced into it, goaded into it, tricked into it, etc. If a player wants to NOT be poisoned when opening a chest they need to be clear and specific and NOT just assume the DM is on the same page, same as the DM needs to be clear and specific to attempt to GET the player on the same page. Opening a chest? SAY YOU'RE PUTTING ON GLOVES. Even if you
don't have any such thing written down as part of your gear, that'll go further than simply saying
for the first time, ever, "Oh! I always
assumed my character is always wearing gloves!"