Wow, this topic is a real flame war. *dons protective suit*
We have to face it - it doesn't really matter whether or not someone wants to learn a language, and it doesn't really matter whether or not someone should learn a language. It's all a matter of perspective. Ideally, if we wanted to have a culturally immersed society, we would get people to learn languages as unusual and unique as they could - but that's not necessarily what's good for society. We're approaching a high degree of specialization these days, and as such, most people devote their time to other studies.
I studied Spanish in high school for four years - not because I wanted to, but because it was part of the curriculum, and at that time there were no other options they had introduced. I admit, I would have loved to learn Classical Latin, and while wanting to learn something does make learning it easier, Latin is still a tough language to learn for the majority of the world. In Spanish, I had to learn a dozen or more conjugations (which were a totally new concept to me, short of -ed and -ing), and then all the exceptions to the rule, with verbs like ir, tenir, and so on. Classical Latin has about three or four times the amount of conjugations per word as Spanish does, and the boundaries for use aren't as clear either - it's not a matter of determining whether or not you're talking about yourself or someone else, but also whether you want to place focus on them, or the action is leading into something else, etc etc. Let's face it: Classical Latin is hard.
That said, I did enjoy Spanish, even though I initially didn't want to learn it. It introduced to me new concepts of grammar that I had never known before. It paved the way for my understanding of linguistics and morphology. It was a good start, and looking back, I probably wouldn't have picked any other language to learn.
Realistically, if we made learning a language with complex, foreign grammar mandatory in schools - Classical Latin, Russian, Japanese, or some other language depending on where you are - a lot of students would have serious trouble dealing with the subject. It would be better - more efficient - to teach students a relatively simple language that still introduces new concepts to them - not because it's easier, but because it makes learning other languages on top of those they already know that much easier. Dropping the anvil on them straight off the bat probably isn't the best idea - start off slow, and build up from there.
In fact, that's actually one of my biggest gripes about 'English' in schools. It's not English, it's just essay writing. Problem is, a student can't write a good essay if their grammar sucks. I was pretty bummed when I took an 'English Language' course, only to find out we spent most of the time writing fake advertisements.
Classical Latin is a great language... For show. Use it for poetry, or prose, or even song. But the sheer complexity of the grammar and the potential for mistakes and confusion makes it a poor and cumbersome choice for everyday use - there was a reason the Romans had Classical Latin (which was formal) and Vulgar Latin (for everyday use). Considering how much bad English there is out there, I'd rather not have those same people butchering what would otherwise be a beautiful symphony of morphemes. Give them something that we can understand even if they throw it in a woodchipper. Something durable.
Conlangs: Elysiani, Melkovin, Solmeia, Sorone, Tartaran
Current Projects: Multiple conlangs & conscripts, Voynich Manuscript translation