State of thornmail, why not make it a component item?

So thornmail doesn't seem very effective right now

It is basically cheap armor but without health and health regen it wont make you that much more tanky. Meanwhile other armor items give us a bunch of other stats aswell as some utilities deadmans plate for example gives us mobility and a small amount of on hit damage and potentially a slow provided you stack up that momentum. Frozen hearth whilst not giving any extra health does give us the aura which reduces everyones attackspeed and it also gives mana and cdr so you can use abilities more often.

Thornmail gives a passive which returns damage on auto attacks. However this is only a small amount of damage. And whilst it never has been very effective vs on hit builds we see more often today riot made somewhat the right move by giving it a flat amount of damage return scaling with armor, this is more effective vs on hits then it was before. But its still not much good untill you get 400 bonus armor becuase only then it starts to become noticeable.

Rather then straight up buffs like make it do tons more damage on return or give it 5000 armor yadayada.

Why not make it a component part of a bigger item. Right now most tank items cost between 2500-3000 gold and get outscaled by the more expensive damage items come lategame. A few good lategame scaling tank items would be nice to have no?

So what if it was part of stronger more expensive item. Lets call it demonic thorned armor.

Price would be something like 3500-3800 Component items: So it would still have the somewhat awkward buildpath to thornmail itself then also a somehwta awkward buildpath to its final form, but getting 2 powerspikes a small one on completion of thornmail and a bigger one on completion of demonic thorned armor. The awkward buildpath and somewhat ineffectiveness of the component items along the way is part of its intended weakness.

So what would the final item look like stat wise and what would it do? Well it is similar in thornmail but stronger and has extra passives+ active. For now ill just go with max cost.

Cost 3800 Armor 115 100% Health regen

Unique passive: Reduces Physical damage taken by 10% Unique passive: Increases effectiveness of all sources of healing by 1% for every 4% missing health. Unique passive: Reflects 15% of the physical damage taken (+ 25% bonus armor) (+ 25% bonus magic resist) from basic attacks and on-hit effects back to its source as magic damage (Calculated before any resistances or reductions are taken into account).

Active:Thorns shoot out in all directions dealing 100% of magic resist as damage to all units within 400 units range and slows them by 50% for 0,25 seconds, And applies a bleed effect dealing 100% of armor in magic damage over 5 seconds applying grievous wounds for the same duration. 60 seconds cooldown

The goal of this bigger item is to help out tanks a bit with a stronger lategame item. It does have its downsides becuase of the awkward buildpath but will eventually reward you with a strong item. The item in general will be a bit better vs AD because of the damage reduction passive making the stacking of armor for its damage return passive less punishable vs items like black cleaver and the last whispers. The demonic thorned armor will also synergize a bit better with magic resist items so its more viable vs mixed damage comps. The increased damage return because fo the extra magic resist scaling also addresses the on hit builds as the return damage has that extra scaling and doesnt punish you for buying magic resist to protect against some of the on hit effects.

Bit of a long post ^^ but i think i managed to explain my idea well enough.