Thank you for opening this discussion, we do hear the request for a generic HTTP output from time to time.
In general, however, we're very conservative when it comes to adding new outputs. They tend to start simple, but require a lot of maintenance work over time, plus Logstash has a lot of outputs already, which can be used at the cost of adding another project. We've added Kafka & Redis to libbeat because these two are really popular as deployment options among our users, but at the same time planned to stop there :-).
In the particular case of HTTP, while it's great that the code change serves your needs, we can expect people to request bulking, custom parameters and headers, authentication mechanisms, different http versions, a.s.o as basic functionality. That's why we're quite reticent in accepting this patch.
Because we didn't have one before, I started an enhancement ticket to measure the interest in this, and we can reconsider if we see this being a must for many of our users.