Yeah, the details aren’t there- but more importantly (imo) is the way the models were constructed.
The building needs to be sectioned to use tiling- things like the wall’s blocks obviously not lining up with the corners is a major turn-off, and it looks lower in resolution than what people need for a FPS, yet higher than you’d want for a racing game or RTS. The textures look they were mainly just dumped onto the models, with practically no hand-painting to show wear, AO, etc. These are all big turn-offs, because the results don’t look professional.
Use transparent decals to add detail areas, preferably designed so that lower-spec games can cut them out to save on draw calls (ideally, use an atlased decal sheet and the decals should be one object). Add elements that can be included to instantly customize each shop- for example, several versions of a signage area, where the game developers just have to add some sign graphics to a sign, reposition / scale it, and voila, a customized storefront.
And strongly consider making both versions that are closed and versions with interiors- no furniture or other fittings, but the basics- floors, walls, ceilings. Lastly, present it as a shot from Unity, using Beast, so that we can instantly see the normalmaps working and the feel of the art as it would look in-game with lighting. A quickie raytrace like that says that you don’t know anything about Unity’s art workflow, and will not sell it to customers.
If I were you, I’d not only do all of the above, but also provide it as a Unity asset with interior lights already installed, so that level designers can drag, drop and then deploy details to make a complete space. Exterior prefab variations would also be really easy and would provide people with something they can use practically immediately.
None of this is very difficult, but it will make a big difference, in terms of how people receive it. Do all that, and it’ll probably sell for $15-$30, depending on how many variations we can build. Ideally, it’d have enough pieces to build a fairly major part of a level design. Remember, people who buy this kind of stuff are generally non-artists and don’t have artists on their teams, and they’re going to be frustrated if they buy stuff that only provides them with a partial solution.