It was absolutely no pain getting my Wynaut to Level 15 ;D
But in all seriousness.. I know I'm in the minority here, but I like baby pokemon (heck, I just remembered even my avatar is supposed to be one! Roosteel, a Skarmory pre-evolution I made up long ago).
1. the concept itself (a new lower stage added to an existing pokemon) is perfectly fine, and it makes complete sense to exist since new evolutions can be added too (which is why both made a debut immediately in gen 2)
2. the actual baby pokemon we have so far: sure, there are some that barely add anything or do something interesting with the design (like Cleffa), but many of them are unique additions (Chingling) that would have been fully accepted if they were introduced right away with their higher stage, and some of them even add a cool twist that wasn't there before (Tyrogue). But even if most of them were just smaller cuter versions of the original that are a pain to evolve, the idea itself deserves to exist and has potential for interesting baby-pokemon in the future.
3. usefulness: as you mention there is one thing they add (special egg-moves), but that could have been done by changing the egg-moves of the evolved stage itself just as easily. However, there is a different and IMO more important aspect that makes baby-pokemon useful: making early accessibility an option (there is no way you could encounter an Electabuzz/Magmar early... a wild Elekid/Magby however is perfectly fine, and already happened in BW2)
4. pre-evolutions can really help flesh out a pokemon by expanding it's evolutionary family, exactly as much as ALL OTHER not fully evolved stages of any pokemon. If you think Bonsly is pointless, but don't want to be a hypocrite, then you should think that Charmender and Charmeleon are just as pointless, because they are all simply weaker steps before the actual desired stronger Pokemon. And if you think that they are pointless because they are too weak, then by that logic so are all the weak pokemon that do not evolve.
The hate baby-pokemon get is undeserved. It's often unfounded and hypocritical, with the only argument against their existence usually boiling down to that they might be taking up sacred dex-spots that other hypothetical new pokemon could have occupied instead (and there I sincerely doubt Gamefreak goes "darn, we need to exclude this awesome pokemon because all the baby pokemon are preventing us". That's just ridiculous.)
I will concede that many of them evolving by friendship is an annoying yet logical choice (at least they should have made their base friendship after capture be like ~175, so they would all evolve quite quickly, merely not Level-dependant, turning it into "just don't throw them into battle recklessly and they'll evolve quickly"-gimmick), but actually precisely half of them (9 out of 18) do not require friendship-evolutions.
But hey, since the beginning of gen6, there is even an incentive to catch a baby instead of the evolved form, because baby-pokemon now have 3 guaranteed perfect IVs, like legendaries do.
The only real issue I have with how baby-Pokemon are currently handled, is the whole Incense business. I am all for consistency, but creating a new Incense for every single line is a poor solution. With the (albeit slowly) increasing list of babies, the Incenses will probably have to be changed to some other method sometime in the future..but whatever it is, I hope it happens earlier than necessary and doesn't prevent both parents from holding an Everstone and DestinyKnot.
There is still plenty of Pokemon I'd love to see get pre-evolutions to make them more interesting and those are my main reason for beign enthusiastic of more baby-pokemon. For example:
-Lapras
-Tropius
-Onix
-Skarmory
-Absol
-Tauros
-Miltank
-Druddigon
-Heatmor&Durant
-Maractus
-Hawlucha
-Zangoose&Seviper
-Girafarig
-Pinsir/Heracross
Is there really anyone who isn't curious about how at least a few of these might look? Do you not have a heart?? You monster! Just kidding. But honestly, Pokemon is great because of its diversity in the creature designs, and if you're one of the people who only cares about the "cool badass dragon designs" or similar, then I can't help you, but some of us like other kinds of designs once in a while
EDIT: I forgot one more interesting potential with baby-Pokemon. Pseudo-baby-stages for legendaries, like Phione. In Phiones case this was a poor execution, and rather just a gimmick in itself, but if done correctly, it could be more interesting.
Imagine for example some of the more important legendaries getting a weaker version of themselves that can be bred from them. Lugia/Reshiram/Dialga Jr. And because the originals stats are so overwhelming, the pseudo-baby stages would get a chance for being competitively viable while keeping the cool type combinations, abilities and all that.
EDIT2: Made a blogpost out of this that might be more enjoyable to read if anyone is interested:
http://pokehype.blogspot.com/2015/06/baby-pokemon.html