Why did TurboTax print out four 1040-ES forms? I have not, and will not need to pay estimated taxes while we are both employed and have taxes deducted from our checks.

If you do not expect to owe at least $1000 at tax time next year then just pitch those 1040ES forms out.  You are not required to use them.   If you think you will owe then it is a good idea to pay quarterly so that you do not end up with a big tax bill or penalty at tax time next year.

Turbo Tax is very conservative and doesn't want you to owe too much next year.  If you are receiving a refund or low tax due and Turbo Tax prepared the vouchers then your tax liability was probably reduced by credits. They might have printed out if you got a one time large income this year like if you took a IRA or 401k distribution.  They are optional to pay and do not get sent with your return so the IRS won't be expecting them.