The reality is this--Most dancers have not aquired the skills to perform ( comp or show ) at slower speeds .

It takes many yrs of floor time , to develop the characteristics , of the the "swing " dances. if you then apply the same principles to Latin, the same rules are in effect.

One only has to look at how the speed for Bolero was danced ( forties and fifties ), and the speed, how its " child "-- Intern. Rhumba was originally performed .

As they say-- the wheel turns .

Laird (6th ed, 2003) gives 27 bars/minute as the tempo for standard rumba.

"The tempi for each dance shall be:

Waltz
28-30

Samba
50-52

Tango
31-33

Cha Cha Cha
30-32

Viennese Waltz
58-60

Rumba
25-27

Slow Foxtrot
28-30

Paso Doble
60-62

Quickstep
50-52

Jive
42-44"

This is per the IDSF Web Site.

Here is the web address.....

http://www.spaeker.de/ru/corules.htm#Rule5_11