why noone get Heart of Flame, Thunder or Ice node

Regardless of whatever build, cold witch, fire witch or lightning, i saw a lot of build but noone take either of those three for there respective element. Is there a reason why?

Those nodes r less effective, than the alternatives for many builds, especially Heart of Ice. The reason why, r the travel nodes, to get there. For the Heart of ice and Thunder u very often need to invest 7 points, to get there and this makes it only 10.14 dmg for each node + 3% penetration, which is not really good. And also a huge commitment of 7 points, to get only 1 notable. Unless u also want those Breath nodes, but barely anybody does, going crit is just so much better.

Heart of Flame is used more often, since u will take those life nodes anyway(if u play a life build) and only 1 point to hop over is kinda acceptable. But still 6 points to get only 1 notable. For that u can easily get 2, sometimes even 3 notables.

Even if u pass buy it, it is a hard decision. 5 points for 1 notable is also pretty big. Especially if that notable is not all that special.

If they would take away 25% inc dmg and make it 10% penetration. Than it may be worth the effort. 15% would for sure bring more builds there.

Imo, those cluster provides only damage. Most elemental skill can also be enchanced by other tags. For example, fireball can also use projectile node to increase damage. Secondly, damage it grants is addition with gear, not a multiplier. Lastly, those clusters are only worth to take if you are caster. Most attack nodes are in a south portion of the tree, so it is not worth going up here just to take those 5 nodes.

In addition, if you want more damage, crit node and crit multiplier will be better option. If you want more survivability, the tree travel there is not quite efficient (mayb for eb + MoM?). The only thing I can think going there is I want to grab double curse and is non-crit caster (No, I won't spent 5 those passive nodes as crit caster. I rather go with crit node and stack a pile of multiplier).

Most caster builds plan on scaling damage increases mostly through affixes on their weapons. Increased damage on tree becomes less valuable.

Those nodes are a lot better in single-element weapon builds (in the pre-Poison era, Voltaxic Rift) or builds focusing on secondary damage (Detonate Dead, Heralds). However, those builds rarely travel go that part of the tree.

thanks that pretty helpful