Most of your comments and in particular with Layer 7 load balancing are restricted to HTTP(S).
Layer 4 and Layer 7 load balancing have their individual use cases. For example with many IPTV applications only Layer 4 load balancing is possible so it's unfair to imply it has to be a choice between the two when sometimes there is no choice.
Likewise in some instances Layer 4 load balancing is used ahead of Later 7. A good example is using port numbers to direct traffic to a set of dedicated Layer 7 load balancers when the target port is 80 or 443.