Why {selbroda}?

[Rob Speer <rob@twcny.rr.com>]

The discussion about {nalmorji} brought up something that's been bothering me.
Why do we use words like {selbroda} at all in Lojban? Doesn't it mean exactly
the same as {se broda}? {se broda} has the same number of syllables and one
less consonant to pronounce as well.

Additionally, the typical usage I see is that people use {selbroda} when they
are using it as a noun, and {se broda} when it is a verb.

1a. mi se broda ti
1b. mi selbroda ti

2a. le se broda cu brode
2b. le selbroda cu brode

I believe that 1a and 1b, and 2a and 2b, mean exactly the same thing. Yet in
the usage of Lojban here you'd see 1a and 2b often, and you'd never see 1b or
2a. The tendency to make nouns single words, while allowing verbs to be modified
by structure words instead, seems rather malglico to me. I can't think of an
example in English that would exactly match that above, but something like
"That is a _lawnmower_" and "The lawn _is mowed_" comes to mind. Is there any
reason in Lojban to distinguish between parts of speech like this?
-- 
Rob Speer