John, the motherboard we use for most builds at my workplace does indeed include the speaker. The board is the MSI H81M-P33, an entry level M-ATX motherboard. Yes, we still build Haswell machines. I remember having seen the speakers bundled with a couple of other low end motherboards but I can't remember which ones they were ATM.
OP- Yes the PC speaker or piezo speaker is an interesting animal. As others have mentioned they used to be included in almost every case (nice big loud ones too) but in the past couple of years it appears that most case manufacturers have chosen to save a dollar and have not been including it. Interestingly, most motherboard makers have not picked up the slack, leaving 90% of people who build a computer today without a piezo speaker, and none the wiser.
Adding the the problem is that piezo speakers are not readily available on sites like newegg or at computer shops. These little speakers are an invaluable tool for diagnosing a computer that doesn't want to POST. They can't hold a candle to LCD POSTers (an actual LCD readout on the motherboard that shows a code for various specific faults) but they are still pretty darn useful for what they are.
I have actually written a couple of angryish emails to a couple of major motherboard makers asking them to include this very inexpensive part with their boards. They didn't write back.