It depends on what you are trying to glue. For some stuff, there are other glues that work as well, but for others, there is no substitute. All glues have requirements for getting a good bond, there is very little in the way of free lunch. Things like Zap-A-Dap-A-Goo are very good at bonding leather and are quite strong and easy to apply, if rather messy, but they aren't a substitute for epoxy.
Not all epoxy should be weighed, some really is meant to be done by volume and the twin dispenser types do an okay job, but not really precise. You still need to watch how to go. The runnier glues are a little easier to meter out, just run a bead of a given length for both, then mix. The thicher ones are harder since they kind of come out of the tube in a blodge. Not sure how to remedy things if you have trouble judging the relative size of two blodges. Laying down a larger quantity than you need, over a measured length, might still work.