Again, if you look at old instruments you will see plenty of glue on the surfaces. Often it's a useful indicator of how they did things: drips run 'down', for example, and show you whether the instrument was built on it's face on a solera. Glue attracts moisture and dirt, so it's nice to avoid having a lot around. These days is also tends to repel a certain class of buyer, and must be avoided. What counts as 'big glue drips al over the place' these days would have been negligible a hundred years ago.
In this case, the glue used is resin of some sort; probably epoxy, and is much more like a 'finish' than the old-fashioned hot glue. In vacuum clamping the top, with the uncured resin, was wrapped or covered with a thin plastic membrane and the air was sucked out. This uses the outside air pressure as a clamp to squeeze out excess resin, which adds weight to the layup but not strength. The excess resin ran down onto the top and was spread into a thin film under the plastic membrane. It is hard to get into such small spaces to clean up the excess in any event, and this type of resin is very hard and strong once it's cured, making it even more difficult. Given that the 'top' is not much more than a membrane to move air, and is at veneer thickness of less then a millimeter, it's simply impossible to get that surface layer off without risking destroying the top. It's possible to think of alternate assembly methods and sequences that would avoid, or, at least, mitigate this, but Smallman has had no need to do so, since he's undoubtedly booked solid for the foreseeable future. In coming years, perhaps, as other makers take this up as a 'standard' method, such niceties will become selling points, and you'll see more effort in that direction.
The resin does, of course, add some mass and local stiffness in those areas. This no doubt alters the way they vibrate. However, the top on that type of guitar is not structural, or even 'acoustic' at usable frequencies, except insofar as it's needed to move air. The structure of the top, and the way it vibrates are governed for all intents and purposes by the lattice. In this respect it's an entirely different sort of beast than a traditional guitar.
Some years ago Tim White designed his 'Chrysalis' guitar. It was an electric/acoustic, built of carbon fiber, which had an open lattice on the top that was inspired by insect wings (White trained in entomology). In use there was a cloth bag that attached around the edge of the back with Velcro, into which you could insert a balloon. Blowing up the balloon produced a membrane between the lattice elements that could move enough air to make some sound. In many respects this is similar to Smallman's design, except that the lattice on White's instrument doesn't carry any string load.