I would bet you nor I have any clue what it adds, how about add a transmitter and reciever all built into the ECU of the car and if it ever lets out the magic smoke it will require a brand spanking new ECU, a tow, and a reprogram all or which would take 2 weeks and $2000 later you can have your car back. Let me guess you forgot that the magic information had to get from one place to another, that alone tells me the battery in the key can't last anywhere close to what a one way remote would last. The cost of replacing a magic key.. not cheap. So please don't bet if you really don't know.
You feel the Keyless push button is the most important, making other models of Challenger "lame", I feel a FAR FAR FAR better suspension setup is the most important change. Amen. Let it be.
The battery in my keyfob for my Nitro has lasted 4 years already. I think it's a $2 cr2025 or something. Not a big deal.
If the ECU burns out, well it burns out--but if it does so it's highly unlikely to be the fault of the keyless entry portion of it. I agree, it would suck to have to replace the ECU, but I think the keyless entry has a negligable impact on the ECU's durability...
Keyfobs are already expensive--try $100 bucks each. This has been true across nearly all models and all makes for some years now, and I don't see the industry trending any other direction. So, again, I doubt the keyless entry functionality is going to really affect the cost of the keyfobs which are already high.
I really can bet you that the transmitter and receiver most likely are integrated into a single ICU, on a corner of the ECU's breadboard, and the antenna is a tiny wire, or possibly sharing the radio antenna which was already there. We're not talking pounds here but ounces at most. The bigger weight might be in the redesign of the door handles.
I really think it adds a negligable amount of reliability risk while adding a huge amount of convenience factor. And for those that don't like it, you can still insert key and twist if you really want to, so where's the harm?