Spare the Dying is definitely full of suck. Cantrip slots are not only precious but you can do far better than this weak-sauce one. If it was ranged and a bonus action, then it would be a good choice, but as touch and a full action, it's really just a waste of a cantrip slot.
Agreed, because healing kits exist.
However, 5E seems to be about having at least the illusion of the threat of death. There is no threat of death if the PCs can just willy nilly stop death savings throws from range and with virtually no effort. I don't think that Spare the Dying should be changed, I think that healing kits should be changed.
As written, the main rules are: 1) Use healing magic (be that ranged or touch or potion), or 2) Use wisdom check touch, or 3) Use a healing kit touch, or 4) Cast Spare the Dying touch, or 5) Succeed on 3 death saving throws.
All of the touch options here run the risk of not being possible (out of range) or provoking OAs to accomplish.
In addition:
#1 uses up a resource (may use up an action)
#2 has a chance of failure and uses an action
#3 uses up a minor resource and uses an action, but has no chance of failure
#4 uses up a cantrip slot and uses an action, but has no chance of failure and does not use a resource
#5 is based on luck
All of these have Pros and Cons in some circumstances. And most of them all require using an action (except certain spells like Healing Word).
By removing the detriment of being touch and an action, Spare the Dying more or less becomes the primary solution of choice and is better as a cantrip than 3 of the other options. It makes death saving throws an extremely rare threat instead of an uncommon threat.
I actually think that WotC got this one partially right. Spare the Dying works for players who want a high guarantee of success without having to mess with keeping track of minor resources. If that is not your thing, then don't take the cantrip. I do think that #3 shouldn't exist. There should be no non-magical guarantee of success of saving a person's life. #3 is the reason people think that #4 sucks, but from a balance perspective, #4 is totally balanced.
#3 is way too cheap and because of that, #4 is way too expensive. I hope that WotC erratas this in one direction or the other.