I think i speak for the majority of players when i say we need more customization options when it comes to our dragons to spice up the world a bit. Looking at the same dragons and skins all the time is boring and makes the world feel dead and repetitive. We need to be able to get more vibrant colors, many patterns to choose from/nest, to be able to change our horns to look different or the tail to have different looks, as well as our spikes. adding options for bioluminescent patterns on dragons also without needing the bio to spit on us when we just simply want to enjoy the scenery and flying around with a less brighter version and different pattern of slight glow on our dragons with being able to choose the color of the glow. Basically more options to make the world feel more alive and colorful instead of the dullness of the same skins and colors everywhere. Letting players have more freedom of customizing their dragons will surly improve the games popularity and engagement overall. Tho it's not likely we are going to get these changes i believe it would improve a lot and can only have positive results!
#Customization
river tendon
pale phoenix
It is coming in future updates
You'll have patterns and colour swatches from your parents and what you unlocked (don't quote me on the last one I just remember a mention)
There's gonna be areas you can color on you skin, some of those have already been showen (about 4-5 regions if i recall correctly?)
edgy veldt
Very much on its way for 1.0.3
fallen meteor
I support the idea of limited customization of features such as horns and scars, and perhaps something like selectable clan-/species-specific patterns of "war paint" (maybe made from berries and/or mud). I understand the upcoming skin crafting options and see that as a good start.
But I specify "limited" because we have to remember that DoD is intended to be more science fiction than fantasy; the lore of DoD is first built on the concepts of species, environmental niche, and genetics. After that, DoD was always intended to be a PvP game (only overwhelming demand for PvE got us that option). Given those, things such as a dragon's general body design just have to be left alone, and alterations should be fairly subtle. Something like a species-specific bio glow is arguably based in a species-specific reaction to bio bile, plus it helps with at-a-glance identification, so it should not have more than two or three closely related variations and color combinations.
Any customization broader than that is, in my opinion, creeping into the realm of another dragon game in development, which obviously should be done with caution if not avoided entirely.
EDIT: Forgot to add that there's also no need to lunge into customization of everything, simply because right now the lack of content (e.g., quests, boss fights) means all there is to do is look at the same things over and over. Adding such content would make character customization less urgent, and we could worry about expanding the latter in the years to come.
hoary slate
Most of what you're asking for is basically 1.0.3 
It won't be "here's a menu upon logging in, choose from any color in existence and paint your dragon" but it will be integrated into gameplay (nesting) and allow for a ton of different unique dragons.
I don't see different tails or stuff like that coming to the game. Like Arborus said that doesn't really make sense for this game. We have different dragon species and they look a certain way in terms of what their body structure is like, where would they suddenly get a different tail from? And if their tail can change, why wouldn't their wings, head, everything? It's not a "build your fantasy dragon" game but a fantasy / semi realistic survival game
The new skin crafting system will give us what we need for variation in dragons, probably much more than what we need - no need to start messing with the species more than that imo
static carbon
Adding onto what everyone else said, when they add the full shimmering caverns biome (where bios come from), one aspect that was mentioned in passing is that all dragons would bioluminesce in that biome. Not sure if that plan was scrapped or not