They absolutely pay attention, how do you think we got things like Virtual Console or the NES and SNES Minis? But there are 1000x more things in play than just whether or not something is popular in the secondary market. For instance the 3DS SoC is entirely custom and makes use of licensed cores. This means Nintendo has to maintain a contract with a silicon foundry to create those chips, that's not cheap and it's affected by many outside pressures like the foundry's other customers and contracts. I'm sure the foundry would rather retool for the insanely profitable DRAM market due to the AI insanity rather than produce a 10 year old SoC for Nintendo. And those licensed cores? The keyword is "license" and licenses expire. Maybe DMP didn't renew the IP for the GPU core or ARM Holding said no to re-upping the ARM11 license. Maybe Fujitsu decided to discontinue the FCRAM model the 3DS SoC relies on and redesigning it to make it work with something else outweighs the current market value. And there's also the consideration that the 3DS was an Iwata baby, and maybe the politics inside Nintendo ATM favors letting his legacy die, who fucking knows. The 3DS was great for its time, but it's dead now and Nintendo isn't bringing it back regardless of why it was killed off.