A nuanced look at Ohmwrecker and its peers
In this discussion, I would like to point out distinctions between Ohmwrecker and its peers, and why people should or should not consider buying this item.
What do I consider Ohmwrecker's peers to be? The armor+health items in the game. There are only four items on Summoner's Rift that have the characteristics of having both armor and health:

Let's bring up their stats, and analyze their similarities and differences as part of the Health/Armor group of items.
Sunfire Cape (2900g) 500 health 50 armor AoE Burn effect of 26-43 damage, increased by 50% against minions and monsters.
Dead Man's Plate (2900g) 500 health 50 armor Gains stacks up to 100 based on movement. Each stack grants movespeed, up to 60 at max stacks. Stacks are consumed on next auto, dealing bonus physical damage.
Randuin's Omen (2900g) 500 health 60 armor 10% critical damage reduction Cold Steel: Enemies attacking you will have 15% reduced attack speed Active: AoE slow by 35% for 4s.
Ohmwrecker (2650g) 300 health 50 armor 150% base health regen 10% cooldown reduction Passive: Builds up to 20% movespeed near turrets Active: Disables nearby turrets for 3s.
You may have noticed some interesting little tidbits. All of the armor/health items have at least 50 armor. Not too shabby for items that provide all the defensive stats you need to survive against physical damage. However, all of the armor/health items have 500 health and cost 2900g, except for Ohmwrecker. End game, where you want as many stats as possible for your limited inventory space, Ohmwrecker can look quite a bit less appealing than these items, purely on tank stat terms. However, Ohmwrecker also has a large amount of health regen, and depending on the champion you're playing, this health regen can more than make up for the 200 health deficit, like shrugging off poke or minion aggro. An extra 10% cdr doesn't hurt either.
These items all provide health/armor, but to make them stand out from one another, they are all provided with different niche characteristics. Sunfire offers damage, Dead Man's offers speed, Randuin's offers the greatest anti-AD as well as a slow. But what about Ohmwrecker?
When people talk about what Ohmwrecker is known for, they bring up its turret disabling effect, and nothing else. Over time, this has caused everybody to stereotype this item as just a turret disabler, and good for nothing else. However, take a look at this:
Cost efficiency: Sunfire Cape - 80.46% (http://leagueoflegends.wikia.com/wiki/Sunfire) Dead Man's Plate - 80.46% (http://leagueoflegends.wikia.com/wiki/Dead_Man's_Plate) Randuin's Omen - 87.36% (http://leagueoflegends.wikia.com/wiki/Randuin) Ohmwrecker - 94.97%, 124.78% near turrets (http://leagueoflegends.wikia.com/wiki/Ohmwrecker)
Based on the stats that Ohmwrecker offers alone, it beats out all the other health+armor items on Summoner's Rift. We can now safely say that Ohmwrecker's niche characteristic is more than just a turret disabler; it is also the most cost efficient of the armor+health item group through its variety of included stats. Health regen and cooldown are stats that none of the other armor+health items give, and Ohmwrecker shares the characteristic of granting movespeed like Dead Man's, though it is a bit more conditional.
Of course, I'm not stating that Ohmwrecker should be the premier anti-AD item to buy on all bruisers/tanks. After all, champions find more use out of the AoE damage niche of Sunfire for waveclear, the unconditional movespeed of Dead Man's to roam, and the maximum anti-AD of Randuin's and its slow to help lock down an enemy AD. However, what should people buy Ohmwrecker for?
Health regen helps shrug off enemy poke and minion aggro. Cooldown reduction helps tanks/bruisers waveclear, escape, or chase. Movespeed when near turrets for escaping/chasing. A turret disabling active for diving or finishing off a turret. People buy Ohmwrecker for pushing/split-pushing!
tl;dr Ohmwrecker is more than just for disabling turrets; it is the most cost efficient of the armor+health items in Summoner's Rift, and offers stats that none of the others do. Ohmwrecker's niche is in pushing/split-pushing.