Yes, in most cases I would agree that expensing machinery offers tax advantages.

Yes, it effectively reduces the cost of owning machinery.

I strongly disagree that you can make a broad statement about actual real depreciation across a wide spectrum of machinery.  We have some machinery which has not effectively depreciated since it was purchased, and some of it has been here for thirty years.   It's ownership cost has been limited to cost of money and repairs/maintenance+insurance.  We also have had a good % of machinery purchases which we have sold for more then we originally paid for them.  I have eight major powered machines on our net worth statement above their purchase price today. The values are lender's values not mine, although I wouldn't leave them there if I didn't agree with them. I would not sell them for less then the value on the books, either.

Repairs and maintenance expenses are already deductible. Modification and impovement of existing equipment can pretty much be expensed, with a few extreme exceptions.

No, it is not a big enough factor to make an otherwise unwise management strategy suddenly be the best choice.

I still think it's a lot like selling grain into a weak market because of taxes, or holding it off of a strong market because of taxes.

Run the business based on business realities and manage taxes as best you can beats run the business "to save taxes" while ignoring business realities.