I know it's already a requested feature, but 90% of the non-planting assets are unusable because I can't change the materials: The geometry of the models may be spot on, but they will never go into any of my models because I want to...
... change what a monitor/screen displays, change a painting/photo image, make a coffee cup or fruit bowl match a colour scheme, make a car the same colour as the client's car, change the wood/finish of furniture to match the decor, change the fabric of seat covers, make the clothing not clash with the scene a person is placed into, change the finish of a plant pot to match the theme of the room, change the rock colour to be closer to the site photos, ... etc.
If a material could be selected from the Enscape window (not just for the Enscape assets) so that the user could edit it's settings 'live' it would increase the ease and speed of the design process considerably. IMHO it would be "a game changer".