Chips are designed to protect our warranty costs.
Epson designs the heads we use and they spec (or design the ink) to be compatible with the heads. (of course they only warranty the head with their ink)
Mutoh optimizes the head parameters and the printer to get the highest performance out of the whole package.
While ink may all 'look the same' when it is dry, the physical and chemical properties of the liquid are all quite different.
They may be incompatible with some parts, pigment sizes can vary, and viscousity and surface tension may not meet the criteria for proper droplet formation.
This can lead to parts that get attacked or dissolved, plugged dampers and nozzles, poor droplet formation leading to print anomolies.
All of these can end up costing us dearly in service calls, which are unrelated to the printer, which ultimately gets passed along to our customers.
Our goal is to have happy satisfied customers who can unpack a printer and get the best print results right out of the gate, and for the long term as well.
Controlling what goes into the printer is our best opportunity to guarantee what comes out of the printer and protect the printer long term.
The printer counts the number of nozzles fired and the number of cycles the pump runs and estimates ink usage and writes this information back to the chip.
If the printer is not maintained properly or the capping station starts to fail, then the seal (capping station) does not seal properly against the bottom of the head and so the pump pumps but does not draw enough ink (sometimes, none) and so the printer 'thinks' it has used more ink than it really has and thus the chip thinks the cart is empty, when it is not. This is probably the culprit of most chip errors (although there are others).
http://www.mutoh.com/kb/entry/95/