Simple ones to "make the game more worth playing":
Voice all-chat & voice chat-channels (so much yes, this will make the game infinitely more fun)
Daily rewards: log in x days in a row and get x amount of silver, play x amount of games in x time and get x amount of gold etc.
Achievements, quests & rewards, for example: ks 500 kills with prodex scout
Hardcore ones to "resurrect HoN":
Tournaments with an (in-game) escrow system for gold, silver, fiat $ & cryptocurrencies
(in-game) Tipping, trading & marketplace system for skins, gold, silver, fiat $ & cryptocurrencies
Reputation system; rate players in terms of friendliness, skill, helpfulness & humor + comment on players profiles & specific games
More leagues apart from the MMR-league; reputation league, gold & silver bet league, $$$ league, troll league etc. + live games
Make the report-a-player system public so everyone can view reports, comment and vote on actions to be taken (+ live reports)
Ultra hardcore ones to make HoN > Dota 2:
Open source the entire game so instead of having a small limited team design a crapload of shiet to make a little money instead let everyone design their own maps, skins, items, heroes, whatever & make it profitable to contribute using tips and collectively funded bounties as well as a in-game marketplace on top of the tipping system (pre-built open-source bounty development systems exists already) -> lots of different versions of the game so a simple version switcher has to be in place
HoN mobile, VR & Savage 3, also open source
These are just exotic ideas floating in space atm, hopefully you guys aren't braindead and will not just come with useless critique that will kill yourself, the ideas, game & community but actually add to them, improve and co-create an epic tangible reality of em'