The time investment to grind out heroes in HotS is still superior by far to other MOBAs.
Polygon compared it to LoL. http://www.polygon.com/2015/2/4/7977165/heroes-of-the-storm-guide
League has a much higher per-hour payout; you can unlock a League champion from the highest price-tier in less than half the number of hours you would need to play to buy a high-priced character in Heroes.
That's without dailies (HotS) or daily first win (LoL) though. Indeed the daily quest is far for efficient in terms of in game currency than its counterpart, the first win bonus. However, it's not enough for HotS to be even close with LoL in terms of grind-speed (though it reduces the gap).
Polygon concludes :
What all the math boils down to is: If you play several hours of League of Legends every day, you’ll accrue rewards at a faster clip than you would if you spent a similar amount of time in Heroes of the Storm. But Heroes is much friendlier if you don’t play every day and your play sessions are shorter.
Which matches your point exactly : HotS's currency system is much more friendly to casual players. However, a more committed player will have a much harder time getting heroes than in LoL.
This is consistent with the game design though, it's gameplay being much more accessible and directed heavily towards "casual" players. Note that I don't point that out as a flaw.
On a side note, I haven't done the math but I'm quite sure Smite is also way faster in terms of grind. By just logging in daily, you can get 5000 favor + 200 gems in one month, which is 500 favor short of 2 heroes (a hero being 5500 favor or 200 gems). You also gain 500 favor each levelup, 100 per first daily win per mode (that's 6 times the bonus per day potentially I believe), and the normal reward for each match which would be around 75 on average I believe. They are also regularly events such as "double everything week-end" (XP, favour, worshipers). 5 heroes are also unlocked from the very start, outside of hero rotation. Feels quick, I'll tell you that.