And rather than just stating an opinion, I'll give you my thoughts, Publius.
Allow me to start with some data concerning the real language I know best : le french.
My go-to grammar,
Le Bon Usage, is 1600 pages long.
My go-to paperback dictionary,
Le Petit Littré, is 2000 pages long and contains around 30 000 entries.
"core french" revolves around 4000 words, though 1000 are enough to sustain daily chat.
Le french isn't the most complicated language there is (it can't be that hard, I manage to speak it on a daily basis), either grammatically or vocabulary-wise.
Let's take a look at crafted languages, specifically those that are used in fiction and try to emulate the complexity and deepness of real ones. Tolkien's Quenya is often considered the most well-shaped and successful of them all.
Quenya's grammar :
http://upload.wikimedia.org/wikipedia/commons/7/75/Neo-Quenya.pdf 128 pages. With small pages. And big letters.
Quenya's dictionnary
http://www.ambar-eldaron.com/telechargements/quenya-engl-A4.pdf scores a wooping total of 131 pages and about 2500 entries, many of them fan-made.
Le not-that-complicated french leaves Quenya in the dust. Woohoo.
Fictional languages can only try to emulate real languages' complexity. They are, by their very nature, barely sketches of what a language is.
Thus, Makkal's Khanid, that embraces this sketchy nature of fictional languages and
makes it part of the fiction, is awesome and rad.
You said something like "we need a structure to speak a language". And I couldn't agree more. Learning a new language is far more than just learning new words.
Let's take a look at another awesome and rad proposition, Ava's Sebiestaaspjak. It only gives a glimpse of what Northern Sebiestor may be, and it was already a difficult thing to achieve -and she doesn't expect people to use it. Many other Eve-related fictional languages are barely a list of words, used to add a little flavor to roleplay.
And guess what ?
It's perfectly fine. Take a deep breath, and repeat after me : "Player-created languages are often just a list of words, by nature sketches, and
it's perfectly fine."
They're not created to be spoken, they're created for the simple pleasure of enjoying ourselves while we roleplay our characters.
If you want to speak another language, Publius, feel free and by all means, learn one. There are thousands of them out there, rich in history and literature. Go get them, tiger !