The problem is that sometimes you don't pick messaging apps you use, your friends/relatives/coworkers do. So to communicate with them you have to use what they use. For example, I don't like Skype, but it's used by some people I want to have connection with and they have no plans to switch/use something else.
Currently I have 6 messaging apps and no hope that I can reduce their number, because I text with different groups of people. The only way to manage this is through self-discipline - I don't check phone too often.
But situation is bad, since these 6 apps doing exactly the same job and there's no interoperability between them.
At present most of necessary software (OS, browser, office suites, social apps etc.) are free in one form or another, so users get in the habit not to pay for it and expecting additional features they want for free.