Is this really that big a problem nowadays?
1. Good VoIP practice is to keep VoIP traffic on separate networks. So there should be very little queuing delays caused by bulk traffic.
2. If you are running VoIP and general traffic on the same link (probable in a home and maybe small business environment) you could have a problem. But…
2a. Many (most?) SOHO links are asymmetrical with the low speed being the uplink. That is the link you can control by setting the MTU. For example, I have an uplink speed of about 3 M bit/sec. A 1500 byte packet arriving just before a VoIP RTP packet would delay the VoIP packet by 4ms. Not good, but not too bad either. And that is the link I can control queuing on so I could set the MTU on it if I wanted. On the downlink side I have about 30 M bit/sec. If the ISP queues a 1500 byte packet in front of a VoIP packet the delay would be 0.4 ms. Not enough to worry about.
2b. Unless you are running a server and dishing up HTML pages or sending email, your uplink packets are likely to be pretty small (HTML queries, DNS queries, etc.) so setting a small MTU on your uplink will not really affect your Internet experience.