Very large site operators use anycast routing[1] which is particularly well suited to UDP DNS; they can easily spread load and minimize latency. If you can leverage anycast directly or indirectly through DNS hosting services then low TTLs are not a problem.
Otherwise, it depends. Even with one DNS query per HTTP request, DNS will only represent a fraction of your network load. It's difficult to make any DNS server break a sweat. More likely the network link will saturate beforehand, causing lots of dropped packets. But it's trivial to advertise and use multiple DNS servers; much more trivial than a web application stack. DNS was built for high availability almost since day 1. This is also why you shouldn't worry too much about low TTLs exacerbating network faults--there's no excuse for not using geographically dispersed authoritative name servers.
For example, depending on the site I'll often host the domain on my own primary name server so I can control records without fscking with a web GUI or REST API, but the advertised authoritative name servers are EasyDNS servers which behave as secondaries mirroring my primary.
The real issue isn't load but latency. That's a more complex problem. If you're not using anycast then your site is probably not big enough or important enough for a few millisecond latency upfront for intermittent page loads to matter. Also, many caching resolvers these days will preemptively refresh records upon TTL expiration subject to usage patterns, which means if you're seeing moderate, repeat traffic then users may not experience any additional latency at all. (Similarly, caching resolvers will often remember failing servers and try them last, regardless of ordering in a response.)
As for how painful are erroneous DNS changes, low and high TTLs cut both ways. If it really matters you should be monitoring this stuff 24/7 (e.g. Pingdom), which means record errors should be quickly identified and reported. If you're setup to respond quickly (which you should be for a serious commercial operation), that augurs in favor of low TTLs.
[1] https://en.wikipedia.org/wiki/Anycast
