So, on a sort of dare, I was starting to learn a new natural language, something I haven't done -- if you don't count my annual two-day frustration with written Chinese -- in a long time. Lesson one gave me an overview: the language was SOV and NA, VP was typically a participle and one of a small number of verbs that did the tense, etc. work, noun agglutinative and on the ergative model. Then came the first of those working verbs, izan, 'to be (permanent or inherent relationship --Sp ser, more or less)(with personal pronouns): ni naiz, hi haiz (the familiar second singular, nice pattern emerging), zu zaude (common 2nd sing. -- that is often hauled in from somewhere else -- no problem), hura da (whoa, Nelly! where did that come from?), gu gara, zuek zarete (no pl. familiar), halek dira. Oh, goody, a whole bunch of puzzles to figure out.
And then it struck me why so many conlangs are quickly boring: they are so damned regular! Most are isolating, so they have no conjugations or declensions, or, if they do, there is just one and totally regular across the vocabulary. The fun, if there is any, is in trying to say strange things with a limited vocabulary -- and some don't even limit the vocabulary. Once you see the program and how it's implemented, there is little left to attract a person, intrinsically. Of course, a person may have extrinsic reasons to go into a language more deeply which may offset its boringness.
But, the reply is, regularity makes a language easy to learn; you can carry over what you learn for one word or construction to another. Maybe. But maybe not. Most people say the hardest part of learning a language is learning the vocabulary and the range of meanings of its words (which never match up with English exactly). The rest is just drill and exceptions. And the exceptions are easy because they are exceptions and so stick in your mind, like unusual thing in every area. And they give some spice (though, admittedly, some pain) to the language.
I don't at this point know what to make of this realization. I'm not about to advocate more irregularities in conlangs, though they would be a Pooh-bah for languages in concultures that purport to have histories (and many such conlangs are irregular in various ways), I'm not going to downgrade a conlang for being to regular (although I may for its being boring). I guess I'll just throw this out and hope it has some effect on the next generation of conlangs.