If you're newer to the game I'll provide some background information on vehicles in destiny. Currently there are three maps in Destiny where vehicles are present and where you can summon your sparrow: Bastion, First Light, and Skyshock.
Bastion and First Light shipped with the base game and were featured in both control and clash in place of Burning Shrine, Anomaly, and Asylum (which were reserved exclusively for the 3v3 and rumble playlists) they were later removed from the regular playlists, replaced by the 3v3 maps, and placed in a playlist called "Combined Arms" which is featured every once in a while.
Not counting your sparrow there are only three vehicles in Destiny: the Interceptor, the Pike, and the Heavy Pike (PvE only). All three are single occupant vehicles and while they can take a beating frankly aren't that great.
From this we can see that vehicles and vehicle combat are mere afterthoughts to Bungie, which is sad because their last franchise heavily featured vehicular combat and team strategy involving vehicles. Large maps are also barely getting a nod as Combined Arms may as well be a half-step away from removal from the game entirely which is sad because that's where longer ranged weapons shine over blink shotgun and Thorn spam.
So let's talk about vehicles in pve. I won't mention sparrows as they are merely ferries from mission point to mission point and serve no combat role aside maybe a lucky splatter.
Currently there are only a couple of story missions and a couple of strikes where vehicles are present at all. There is one story mission on the moon where you actually see enemies occupying vehicles and a rare public event in the forgotten shore and in the ember caves where enemy pikes are shown. In all of these cases it is easier and faster to just ignore these vehicles and continue on your sparrow and just skip these moments.
Turrets laughably only exist in one small part of a miniature mission on the moon for the queen's wrath. Despite this that part was amazing and I'm sad the whole mission isn't wave assault on a turret.
Pvp side of things the interceptor is really the only good vehicle and even then because there's no hijack option the easiest way to take them down is to shoot the occupant out the back. Heavy pikes don't exist and pikes are kind of just there and most people simply ignore them. Turrets are only used to take out the vehicles that no one uses.
So what should happen?
Either decide to bring vehicles into relevancy or remove them entirely. This limp state they're in right now is honestly an insult to how you've handled vehicles in the past.
If you want vehicles to become relevant you need to make them powerful enough to be coveted, feared, and targeted. You need to foster cooperation though multi occupant vehicles (Destiny likes groups of three why not add a three player transport?) Most importantly you need actual big maps for vehicles to be effective and a legitimate big team playlist for large scale battles to actually happen. These maps either need to be brought back into the fold of regular 6v6 or kept on a permanent playlist.
In pve you need to make vehicles more of a necessity in certain areas over simply skipping over in a sparrow. Moments where you're pinned down by enemies in vehicles (not mini bosses, there's a difference), like a pike chase sequence or you're trying to escape the cabal and you have to be quick and mobile to escape all the dropship guns laying fire on you. Simple moments like this break up what feels like the same three wave defense and door opening missions over and over again and keep the content fresh.
Have a vehicle idea? Vehicle map ideas? Post em here and hopefully bungie can see that more vehicles are pretty much always better.