>>620
There are reasons, but it depends on which one you're learning. The biggest one is that artificial languages are almost universally easier than natural ones, unless deliberately designed to not be.

Esperanto failed (admittedly, if you look at the historical record, there was a lot of deliberate effort to kill it), but has a large userbase and is relatively easy to pick up. You'll end up talking with other language nerds if you're into Esperanto, too.
Interlingua is useful if you want to pick up a generic Romance language (and thus you'll also actually be able to use it in real life because it is explicitly designed to be intelligible by speakers of a lot of languages). It is also supposed to be quite easy, and you could branch off into learning a specific real Romance language from it. Unfortunately, the number of outright Interlingua speakers is fairly low, so you might not be able to to easily understand any responses you get when speaking it to say, a Spaniard or an Italian. Same shit applies to Interslavic, which is a constructed generic Slavic language and has similar design goals for people traveling in that area of the world.
Toki Pona is tiny (maybe like 140 words right now) and you can pick it up in like 2 months if you're rushing. It is definitely deeply flawed for general communication (some of the flaws are by design, annoyingly enough and could easily be fixed), but not totally without merit. It has a high userbase by conlang standards (not many people), but most users are terrible at it because they "know" it rather than actually know it and when you try to understand them, you realize they never actually did learn the grammar (which is admittedly a bit too simple and completely lacks any kind of guide rails). It is a great first step in a language learning journey though, because it exposes the user to a lot of concepts about how another language could work while also not needing significant effort to learn.

tl;dr:
shit's easier lol