If you are thinking about radiation from your PCB and sensitivity to external disturbances then most important thing is to have continuous GND at one PCB layer to ensure for each signal track the closest to it return path (works good in both directions (radiation/sensitivity)). Even with 2 layer PCB in many ceses it is possible to have continuous GND at one layer. My example:
If it is not possible then it is reasonable to use 4 layer PCB just only to have continuous GND layer.
If you are thinking about interference between your own signals than increasing distances between tracks can be helpful. But it not calls for evenly spacing. You should understand what signals you have in your tracks. If for example you have 3 digital lines driven directly by the IC and one line coming to it. And you know that this one line is driven relatively weakly (like 1k internal resistance) than you should try to make distance between these 3 lines and this one being bigger and you need not to worry about distances between these 3 lines. I had such case with lines filtered at shield border. Inside shield input lines were driven weakly because of filtering and output lines being paralel to them were driven strongly as filtering was still in front of them.
I have seen the information that having clearance between tracks being 3 times track width is almost always enough to avoid interference.
In typical case I have track width 0.25 mm, clearance 0.2mm and grid 0.1mm. So routing according to grid I place tracks with 0.25 mm clearance. If I have a room I route them one grid step farther.
You never need exactly evenly spaced tracks so KiCad is not asked to have such feature.