Any enhanced bass I suggest is placebo, but it is your ears and your speakers. I can't tell you what you hear. Anyway, my mains sit of ceramic elephants so I use a bit of that same carpet no-slip so they don't rock. ( not the best sonically , but high WAF)
In theory, a speaker that was pretty lightly built, with big woofer and tremendous power could, in some extreme case, the cabinet displace enough for doppler effect. It does not violate the laws of physics, but I suggest exceeds the practical. In some cases, the laws of physics is not violated is a flimsy cabinet did not transfer some of that to a thin flimsy desk top causing resonances. Nothing says it can't, but nothing says it likely will.
Do you find it ironic, they also sell spikes to increase the coupling to the surface with the same magic results promised?
The funniest is the spikes sitting on a plate, sitting on balls in cups. Some magic about allowing displacement ( enhancing doppler) and "grounding" the speaker. I was at a very high end store and for speaker demo, he was carefully using a level and adjustable spikes between the speaker and stand, that was sitting on thick carpet that was almost unstable. They did cater to the ego brands and they did not try to sell me on them. The only way small stores can stay open is to remove some excess cash from very rich fools.
The primary function of all this is to transfer your money that should have been spent on better speakers into their boat payment. Your solution is excellent, leaving you funds to buy more music.
Never had a speaker come with feet either, though stuck some on over the years.