Now, speaking as a user discussing with another user:

First off. You're clearly assuming that I'm arguing against Esperanto usage, when I'm mostly talking about its design demerits, and how they descriptively impact its usage. Specially Esperanto as designed by Zamenhof back then; that, as yourself highlighted, is not the "same" Esperanto as now, and being promoted by plenty Esperantists under the incorrect claim that "you only need to learn 16 rules! It's so easy~" [more on that later].

And keep in mind that what I'm saying comes from the PoV of a conlanger, not the PoV of someone soapboxing which language people should use. When it comes to prescriptions of which lingua franca people should use, I'm simply lukewarm towards Esperanto.

With that out of the way: some of the claims in JBR's page are garbage, but some are actually sensible, even if you dislike them. (And some are as outdated as its layout.) It's still good discussion material about the language, regardless on how it affects its community.

That’s not “poorly designed”, that’s a misnomer for “not perfect enough”. Perfectionism is the enemy of good. And Esperanto is a working language which is in itself more or less consistent. [NB: emphasis in the original]

The difference between "poorly designed" and "not perfect enough" is solely where you arbitrarily place the quality threshold. And the exact same argument that you're using can be used against you:

• A natural language, by setting the bar lower. "Perfectionism is the enemy of the good. [Mandarin | English | French | Latin | Greek | etc.] is a working language which is in itself more or less consistent. Why bother with Esperanto? Because natural languages are «not perfect enough»?"
• Another conlang over Esperanto, by setting the bar higher. "[Ido | another Esperantido | Toki Pona | Lojban] is a working language which is in itself more or less consistent, while Esperanto itself is just poorly designed".

So, where do you put that bar? And more importantly, why you put it there instead of higher or lower?

One could argument that its inventor did not want to create the perfect language, but a working one which is the template for the actual language, which he knew would evolve out of it. Today’s Esperanto is already a different one than the one published in 1887.

I'm not going to assume what Zamenhof "wanted", regarding design, but the idea is rather curious. Contemporary Esperanto does show some developments, as if the community was addressing design issues from its original design. From the top of my head: /x/ seems to be losing phonemic status.

And? What is that for an argument?

It is an argument against how Esperanto was designed. It is not an argument against (or for) its usage, although it's one of the factors behind it. Drop down the defensive tone and you'll see.

It has 16 rules, which are still 16 rules, which are rooted in how other languages do their thing.

It has a bazillion rules, as any speakable language. Complexity is intrinsic to human linguistic communication; the very fact that Esperanto works shows that it does not have "just 16 rules". Except that those rules are not usually acknowledged by the linguistic community, even if they were the ones making them.

And which features Zamenhof took from those other languages can be criticised. For example: the article + case mark combo. It's unnecessary - you need to know two systems to be able to proficiently use the language, when one would do.

Then the rest of the booklet which the inventor of the language published was full of exercises to show the implicit rules.

Let's call wine "wine" and bread "bread": implicit = hidden.

Still, these rules are useable and give people enough to learn the language.

Esperanto as designed back then was not useable, without plopping ad hoc rules borrowed from the community's native languages. And it's currently useable because of those rules being incorporated into the language, even if implicit = hidden.

One could even argue that the 16 rules are not just 16 of the kind, even when reading them they have sub-parts, are longer than just say “-o marks nouns” or something. Criticizing Esperanto because of them is just an act of ill will. “Look ma! They are not just 16 rules … looolz!” no shit Sherlock!

And I could argue that orange is blue or that potatoes grow on trees.

And, again, I'm criticising Esperanto's design.

TL;DR: I’m calling the claim “poorly designed” as nonsense and ANY re-iteration of it as trolling or dishonest attempt to derail any rational investigation of Esperanto as a language.

And curiously enough, in no moment you actually addressed the claims. Instead you:

• threw some argumenta ad hominem - attacking JBR instead of either his claims (or mine - refer to the rest of the thread);
• minced words in a way that fakes some qualitative distinction between "poorly designed" and "not perfect enough" (the diff is quantitative, and arbitrary)
• throwing what reads like a tantrum. Or worse, soapboxing - rather fitting, since the activity in your profile boils down to "jump at any opportunity to talk about Esperanto, assume that the world is against it, and defend it from them".
• claiming that I'm trolling or being dishonest.

Rational investigation requires criticism, like it or not.

(By the way. I believe that a lot of the design issues that I mentioned will be eventually addressed within the language, not by ditching Esperanto but by slowly changing it, in a mix of natural evolution and co-designing.)