Are "li", "la" and "e" necessary?

[janPeka]

I have been delving a bit into Literary Chinese, and based on what little I have studied, I think "li", "la" and "e" are probably completely unnecessary... ambiguity could be resolved based on context in a complete text or conversation. That said, they do make life easier, especially for isolated phrases.

[janKipo]

My memories of Chinese are weak and scattered but I seem to recall any number of particles which demarcated sentence parts. Many were optional in stereotyped structures, to be sure, but then the structures were very stereotyped. In any case, that is Chinese and this tp, very different. I admit that I can often supply missing separators on undifferentiated strings, but these are often guesses and more than occasionally wrong. So, I think we better keep the separators.

[uteose]

There are a few cases where I think without them ambiguity is impossible to avoid, for example

mi moku (e) telo (e) kili

Did I drink water and eat fruit, or did I drink fruit juice?

There are also some compounds which rely on these words - e.g. 'ken la' = 'maybe'

Certainly, there are cases where they do look more optional - the common one being that li is required when it's not mi or sina, e.g:

mi moku
ona li moku

I'm sure someone else can explain why they are used in this case.

[janKipo]

Look at tp FAQ at tpnimi.blogspot.com for more details. Basically, without those breaks (and we need one for prepositional phrases, too) we would just have a string of undifferentiated words with no visible structure, since tp has no rigid word classes. We could take any substring as subject, the next as verb and one more as object, any which way.
I admit that 'ona' is a tricky case, but the thinking seemed to be that it was more likely than 'mi' and 'sina' to get modifiers and also that it was far less common. The latter has turned out true so far, the former less so.