Respectfully, I don’t think you understand the context of this problem for many site administrators.
1. The PHP project itself has EOLed (for example) 5.3.3, however distros continue to support it with backported security and bug patches of their own.
2. PHP 5.3.3 (with backported security and bug patches) remains the default in CentOS 6.9, which is supported until 2020. More recent versions are not available via their repositories. Hosts would have to upgrade PHP outside of the CentOS packages and assume the maintenance burden from then on.
3. About 50% of sites running PHP as of August 2017 are at versions less than 5.5:
https://w3techs.com/technologies/details/pl-php/5/all
https://w3techs.com/technologies/details/pl-php/all/all
4. Updating PHP is not like simply updating my Web browser. Real-world production hosts like mine are filled with various work by various developers over at least several years. Bumping PHP further than a maintenance release would almost certainly mean unnecessarily breaking things that are hard to find, probably tricky to fix and written by people I’ve never met who are long gone.
I think it might be reasonable to assume that the language features you’ve used that require PHP 5.5+ were not actually necessary for you to develop this plugin.
I hope you will consider making sure this plugin is available to the greatest number of real-world users by ensuring it works on a really strong majority of servers in the wild.