Most irregular verbs also serve to increase bandwidth though: You can say "I ate" faster than "I eated".
"Going to the store" (rising = question)
"Going to the store" (flat or descending = statement)
For tonal languages, the use of tone as a distinguishing characteristic is similar to any other phonemic characteristic you would typically have to distinguish words in any other non-tonal language. For instance, in English, voicing is a distinguishing characteristic that differentiates the words "pat" and "bat". Similarly in Mandarin Chinese, tone is a distinguishing characteristic that differentiates the words "mā" (mother) and "mǎ" (horse).
Stress in English is phonemic however, viz. this minimal pair:
"rekord (record, n.) vs r@"kord (record, v.)
This is a regular phonological process in many English dialects to derive verbs from certain nouns (or is it the other way around?). Future English could turn this into a tonal distinction - I think that has a precedent in Swedish.
They are hard for western learners but only because we are unused to treating tonal information as important.
In fact because of tones and limited pronunciations available I have found that I feel Chinese is more tolerant of bad or variant pronunciations than english(Assuming you can get tones right but there are really only 5 tones to learn). Tones just make a few more bits available for error correction.
As background I have studied chinese for 8+ years and lived in asia for a couple of years as well.