I doubt if many similar pieces of equipment being manufactured today, or even still at the design stage, have Gigabit ethernet ports if 10/100 will suffice.
Bear in mind that whilst the difference in cost between the two components may only be a few pennies, the production runs for the finished equipment is often in the hundreds of thousands, so multiply that up and there are considerable savings, (ie more profit), to be made for the manufacturer. This is true at all price-point levels in the market.
Now repeat that for every other component that can be "down-specc'd" to the minimum required and the savings/profit really mount up.
Having said that, component costs etc don't always have a big effect on the selling price of an item - it is more, "what can we get away with charging?", tempered with cometition between manufacturers etc.
Back in the early 1980s, when the legal CB boom started, the average "rig" sold for around £100 in the shops. One of the many specialist magazines of the day took the lid off one rig and totalled the whole component cost to be around £5 or so!
Obviously there are design costs, manufacturer tooling, packaging, shipping and retail costs to add in, and everyone in the chain needs to make a profit, but just 2-3 years later, when the CB "craze" was fading, those same rigs were selling new, for just £30!
