I imagine it’s a combination of neccesities (to him), magic stuff he needs, and random shite that he has no idea what it is or what to do with it. Very crow-brained behaviour
One remnant of the past is the Softmap building in Akihabara, formerly known as Tsukumo Akihabara Ekimae, with the iconic escalators. Here is was in 1980:
This building has changed hands quite a lot and this has affected it’s techno look for the worse.
Photo of Luigi posted on Nintendo of America’s various social media accounts in 2013 as part of the Year of Luigi celebrations, featuring Luigi making a joke about his height difference to Mario.