Carpet Spikes, WHY?

I can't really speak for other spikes, cones, or points, but Star Sound's Audio Points do nothing to isolate bass from the floor.

The Audio Points act somewhat as a conduit to expedite resoance away from the speaker (or whatever) and down in the flooring system and then to ground. Thus keeping the speaker, (or whatever) from allowing these vibrations to build up within and reek havoc on the sonics.

And yes, in the proper setup, one should anticipate significant improvements in the bass as well as elsewhere.

-IMO

The "word on the street" is that you need spikes if your wood floor is less than rigid (e.g., in a pre WW-II frame house). If you live in a well-built home or apartment building, you don't need them for sonics (Maybe you need them if you have ultra shag carpeting).
However, if you're an apartment "Dweller", spikes are MANDATORY to isolate your sound from your neighbors (nothing transmits bass like a speaker sitting on the floor).

No, not less.
It will tighten your bass up however. It wil also bleed into other rooms a little bit less.