Suppletivity, such as in the following examples:
be, am, was, etc.
good, better, worse
parvus, minor, minimus (Latin)
bonus, melior, optimus (Latin)
malus, peior, pessimus (Latin)
sein, bin, war, etc. (German)
gut, besser, am besten (German)
seems to appear in words which have a more basic meaning and are obviously more frequently used than most other words. Do we know of any theories about the linguistic mechanisms in suppletivity?