Can I do without tile grout if I'm happy with the color of the dried tile adhesive? Just gently trowel the adhesive as a grout and leave it that way.
On the surface of the mortar is formed polymer film, which is impermeable to water and mechanically stable. Tile adhesive absorbs water very well and is not mechanically resistant. I would not recommend using tile adhesive instead of grout.
Tile adhesive absorbs moisture, while grout is much less soaking wet. Tile glue is almost not resistant to abrasion and scratching – grout is stronger.
The most expensive tile adhesives in the manufacturers' ranges (like for mosaics, granite) come close to grout in these properties, but do not compare to them.