I must admit, one thing that really confuses me is why people are so against pre-evolutions of pre-existing pokemon.
Firstly, people who argue against them only ever talk about it from the standpoint of the games - although at this point it is one of the biggest parts of the franchise, they still have comics, trading cards, spin offs, merchandise that ranges from stuffed toys to limited collectibles and the freaking long-running show. The games may need to be balanced with what they put in, and all seem to serve some kind of function but at the end of the day, they have to keep these in mind too - many need to be marketable to more than just the competitive battlers of the mainstream games. It's because of this that pre-evolutions can be so good outside of the games for Gamrefreak and Nintendo - mostly in Japan where cuteness sells.
Bonsly and Mime Jr were great ways to add both cuteness and publicity for the 4th generation all the while adding new stories to tell around them and characters to play with in the show. Brock being a typical breeder, its unsuprising he also got his hands on Happiny that generation and don't forget Mistys Togepi! (though that was introduced in the same generation as its counter parts, I know!).
Secondly, they clearly serve a function in game too. For baby stage Pokemon like Togepo and orginaly Riolu - they can act as a better test for people who like to put a little added effort into raising a Pokemon mid-play-through for a reward with a Pokemon that often can't be found in the wild that generation. Most people chuck them aside due to the extra effort it takes to raise during the play-though but it acts as a nice little unique reward that not to many friends of yours may have put the effort in to raise as of yet. Not too many people I knew sported a Togetic in the second gen during their playthrough - mostly because the younger players tend to put these babys to the side.
The second function - and arguably the best - that they serve in the main games is that they introduce a Pokemon as a possibility to your team far earlier into the game than previously or make a rarer pokemon less elusive when it didn't need to be nor seemingly was it intended. Chingling being a good example of an unintended rarity (with chimecho in the 3rd generation being unnecessarily isolated. Mime Jr, Bonsly and Munchlax are all great examples of one-off Pokemon becoming more rediliy available outside the generations they were introduced.
A third function that is just begging to have more emphasize put onto it is breeding for pre-evos. Pre-evos have been used to make their evolutions easier to get - but what if it worked the other way around? At the moment, getting a pre-evo via breeding requires you to have a held item on the parent. What if this was used as the only way to get one or two pre-evolution? And what if these pre-evolutions actually had a split evolution line - meaning the only way to get this other line of Pokemon was via breeding with the other line actually found in the wild? Sort of like how Wirmples line splits into two affter the first evolution, only one half only being able to be triggered by conditions the baby Pokemon is put under - with the baby Pokemon only found via breeding.. adds more challenge to thous who wish to catch them all - and even better if these Pokemon are viable for battle usage as a good reward!
So yeah, my point being that I would LOVE another SMALL handful of pre-evolutions this generation. They serve a great purpose to the game and shouldn't be belittled to a relative size as their physical form... They at times may be gimicky, but unlike some, they are a functioning, multi-purposed and well thought out gimmick for both a good for the players and business point of view.
(Disclaimer: I don't want every rare and single staged pokemon to gain a pre-evolution - pokemon like Syther, Lapras and Skarmory are fine without a pre evolution - Lapras arguably without and evolution too)
I would quite like to see Nosepass get one though.. Maybe Torkoal could get the Roselia treatment, with both a pre-evo and an evolution. I would prefer to see the second and third gen get some for theirs that have been waiting so long get some spotlight before the 5th gen gets yet even more right affter release. Though Druddigon wouldn't be a bad shout...