Weapon Speed factors are broken for light and heavy weapons...This System only makes sense, when you allow attacks of opportunity as soon as an oponent with a short reach enters into the fighting distance of someone with a long reaching weapon. From that Point on it gets to complicated, which is not the base idea of D&D next.
Agree that
ideally, if we're going to use Weapon Speed, it should be influenced by Reach. I'm very familiar with Sean Reynold's rant from a decade ago about how weapon speeds are bogus, and with Hackmaster's system that does away with rounds and uses Reach as a tie-breaker for when two foes close ranks. I've contemplated but never implemented a fix.
Making Reach relevant without dragging your combats to a crawl:
1. Home-brew weapon speeds that take into account Reach. DEX characters already benefit from a bonus to Initiative, and there is valid criticism they get a "double dip" using finesse weapons by getting another +2. With a d20 variant, it's not huge, but if you want realism, you could craft your own with rough ranges of +2 to -5.
Up front a lot of arbitrary work. You could take inspiration from the free online Hackmaster rules, but you're opening yourself up to player argument if everyone is not in agreement.
2. Alternately, if a melee action is declared and an enemy closes rank, whoever has Reach can opt to strike first no matter the initiative (though you don't get to Act twice, you could still move when your initiative comes up). This would reflect the difficulty of getting into range of a sword wielder using a dagger. After closing ranks, initiative applies as normal. If the enemy disengages, whether by choice or being forced away (e.g. shoved or
Thunderwave spell), the Reach rule applies again. If both Initiative and Reach are exactly the same, resolve with a d20 roll.
This requires a TON of work. Hackmaster assigns a Reach number to each weapon reflecting its size and maneuverability, then a modifier based on the wielder's size, such as -1 for short.
In conclusion, it may not be easy up front, but I think it could be done.