Agreed on all counts, no technical argument from me. I would offer that relative repeatable values are close enough to figure out if something is wrong, especially once you have kept an eye on things long enough to know what is normal for your truck. If your differential normally runs 80 degrees above ambient and is now 150 over, something is going on. It doesn't matter if it is 145 or 151, just that it is abnormally high. Some trucks do not have enough empty dash space to add a lot of independent gauges, and I don't think you need individual gauges for values that don't need constant attention, such as you would on exhaust temps on "tuned" diesels.
To each his own; you have to know what you've got and how to make it work for you.
