No no, I get it. I still think it's not worth the effort though.
Like, let's say the task is making an encounter with a bunch of goblins led by a goblin vampire. You could say "apply vampire template to goblin" or "apply goblin template to vampire", or you could write down "goblin vampire - 40' MV/fly, 50hp, 16AC, 1d8+3/1d8+3, bite 1d6+3 (heals for amount damaged), Regenerate 5hp/round, Dominate (DC 15)" and be done with it. Sure, it won't be statistically accurate to either goblins or vampires, but it will do the job for the non-scrutinizing players, assuming it has AC/hp/damage output appropriate for the required encounter CR.
Sure, you ca do that in the early editions and 5e, maybe even 3e, but 4e monsters are more complicated. Taking your example, here is a fairly typical goblin. It's an early version and the numbers are off, but it will do for our purposes.
Goblin Tactics is something all goblins have; if somebody misses them they can scooch away without provoking an opportunity attack. This particular goblin also rages when he loses half of his hit points.
Then this guy gets killed by a vampire, and he gains these characteristics:
I have a program that applies templates and lets you export them. It's easy to use but damage values always need tweaking. This is what it gave me, without the tweaking (but note I don't usually bother doing this because I just plug the data into macros on a token in my VTT):
Our goblin vampire get a fair bit more complicated, but he also counts as two creatures, so it evens out. The sheer diversity of abilities present a challenge when making up something like this on the fly.
One thing I like about this is that the consistency lets the players learn about their opponents, and apply that practically. All goblins have Goblin Tactics - and they can teach it to their pets, so if they know that, and a wolf shows up using Goblin Tactics, the players can infer that it was goblin trained, and there may be goblins nearby. If the PCs have become good at fighting goblins, that is going to be helpful fighting a vampire goblin.
Bandits and brigands often have the Surprise Strike attack, which can be countered if you know about it; if you served in the military, and the bandits instead have Takedown Strike, you know that they were originally mercenaries.
Vampire thralls have a difference suite of powers than vampire lords; also there are variant vampires, so if you are dealing with a lot of vampires you can start recognizing strains of vampirism, and vampire "families."
So the consistency is something I am going for in my game. I may modify a template, or make my own template, or a custom power, but I always make sure that creatures that have culture, or training, or heritage in common, will also have a player-recognizable mechanical feature(s) in common. I've seen players get pretty excited when it suddenly dawns on them that there is a connection between this thing, and what they encountered earlier in the campaign, or in a different campaign, and it's gratifying.