Much easier for someone who is speaking his native language --which uses the subjunctive-- than for someone who is coming to the language from a mother tongue in which there is no subjunctive.
What language are you talking about? Every language I've studied has a subjunctive. I'm sure there are ones that don't.
People who speak Chinese or Japanese have trouble with grammatical number (singular and plural), too. Are you going to leave it out because it might be hard for them?
See above.
No, it's not a problem when you standardize pronunciation.
And by what kind of brutal worldwide dictatorship will you accomplish that? No one has ever done that, not even in
France, which is the most linguistically-controlled place on the planet. In the broadly-spoken linguas franca we know of, pronunciation is a local matter; no one tries to speak Swahili with a native accent (the small number of native speakers do it without trying; the rest don't bother).
Just because they failed in the past doesn't mean they would fail in the future.
Unless you do something very different than the previous ones did, it kinda does.
Which is available to a much smaller percentage of humanity than an alternative language might be because it (English) is so hard to learn.
English is more widely spoken on this planet than any other language, even if you lump everything called "Chinese" together (which is kind of like lumping everything called "European" together). No artificial language has come close to those numbers. They're marginal at best.
What method will you use to devise a language that's easier (for everyone!) to learn than English? I think you underestimate both a) the difficulty of the task of creating a language, even if not absolutely from scratch, and b) the difficulty of weighing all the different approaches to language to maximize ease of learning.
Esperanto was only trying to combine and simplify European Romance languages. The only one that really tried to make its vocabulary and grammar universal (with population weightings for greatest-good-for-greatest-number) was Loglan, which is universally (well, except for a few crackpots) held to be a complete disaster: not one person has EVER learned to speak it.
Do you have some method in mind? People with lots of linguistic training and years of experience learning many languages have tried, and failed. What makes your effort different?
I think you missed my point. You don't attain global market hegemony by being virtuous. You attain it by
being adopted most widely despite lacking virtue.
Yet English has virtues not shared by other languages. It has the largest vocabulary of any modern language (and historically only Ancient Greek has it beaten); this makes subtleties of meaning available which require many more words to express in other tongues. What's Spanish for "I'm alone, but not lonely"?
And in general English is quite compact. Chains of nouns modifying each other are one good example; try translating "There's been a malfunction of the White House press briefing room podium sound equipment" into any Romance language, and you'll see one reason English is so widely used.