Thing is that while Hit Dice superficially serve the same purpose as healing surges (enable healing in-between fights), the way they work is almost exactly the opposite. To wit:
- In 4e, you have a mostly-fixed pool of healing surges, and the value of each scales with your hit points (and therefore your level). In 5e, each hit die remains the same absolute value, and you gain more of them as you level up. This might seem similar if you only look at the amount of healing done, but it means they work very differently in practice.
- It means that using healing surges as a cost for things always feels like the same cost. Meanwhile, a hit die is a big cost at low levels, and a small cost at high levels.
- It also means that the effects of spending a healing surge always has the same proportional benefit. The 4e Warlord's Inspiring Word lets the recipient spend a healing surge and recover an extra 1d6 hp (plus 1d6/five levels above 1st), which means it's always going to have about the same benefit. You're a 3rd-level rogue with 36 hp? That's 9+1d6 hp back, about a third of your hp. You're 13th level with 88 hp? That's 22+3d6 hp back, even more than a third (this is because 4e hp, and therefore healing surge value, is front-loaded while the 1d6/5 levels scales linearly)! But compare this to the closest ability available to the 5e Battlemaster? That would be Rally, which gives one of your allies temporary hp equal to your superiority die plus Charisma modifier. If you're a 3rd level rogue with 21 hp, getting 1d8+2 or so temporary hp is pretty sweet, that's a bonus of about 33%. But if you're 13th level with 81 hp, getting d10+3 hp is only about a 10% increase, which is just ridiculously low.
- 4e also fuels almost all your healing with healing surges, not just out-of-combat healing. There are a few abilities that don't use healing surges, but I can't recall any that aren't daily powers in themselves (which makes selecting them basically the same as buying more healing surges). Your Second Wind ability? That's a healing surge. The warlord using Inspiring Word or the cleric using Healing Word? That's a healing surge. Drinking a healing potion? That's a healing surge (but using a fixed value instead of your own). 5e, meanwhile, has plenty of non-HD-based healing. You have the Healer feat, cure wounds, healing word, healing spirit, lay on hands, and so on, that are all independent of HD. Of course, that meant that you had a proportionally larger amount of healing surges – the baseline was 6+Con bonus, and it topped out at 10+Con bonus. So you'd probably be able to recover ~150% to 300% of your max hp over the course of a day, as opposed to ~100% as with hit dice.
Thanks for the explanation. Not sure I really care for the 4e Healing Surges. :-\
So as you go up in level, it takes more to wear you down (more hits, bigger/tougher/more dangerous hits, higher level spells, etc.). But it always takes about the same number of Healing Surges to get you back up to max? That seems off balance...
Also, if I am out of Healing Surges and the Cleric casts a healing spell on me, I get just a small benefit from it? Why have a Cleric? Let's just grab healing potions and be done.
Maybe I have been conditioned from all the other D&D editions I have played, but I
like the traditional trope of higher level heroes needing more healing to get back up to top form. And I also like the 5e view of having separate internal (Hit Dice) and external (Clerics, Paladins,
cure wounds scrolls.,
potions of healing, etc.) healing as resource pools.
EDIT: OK, I was being a bit cheeky about needing Clerics. I am sure they did other things in 4e than healing!
