That said, the typical period of upgrades between major revisions in the software industry is within the last year. -Josh
You need to compare like with like. The one year of updates you refer to usually applies to software that comes with an update every year or so, often minor "utilities", so you end up paying for a new version after about a year. In effect, this is subscriptionware.
In the case of Opus, you can wait three or four years for an update. So if you buy today at the upgrade price you will end up paying less per year than you will for those annually updated packages.
And in the three or so years of an Opus version you will also receive substantial incremental updates for nothing. One of the programs I buy operates on an annual cycle with upgrades every 15 months or so, long enough to push you out of the free upgrade period, with new "major versions" offering tiny changes of the sort that come along all the time with Opus.
Other software is moving firmly towards being rentware. For example, it was only when users screamed loudly that Mailwasher relented on its annual fee regime and sold a "lifetime" licence. (A lot of customers thought they already had that in the previous version.)
If you look at other software that releases on the same sort of cycle as Opus, Microsoft Office for example, or anything from Nuance you won't even get a discount for the upgrade.
I am open to persuasion, though. Just as I have given examples of software that does not fit into your criterion, I can add more, perhaps you can point us to software that does offer free updates to "major revisions", not just cosmetic tweaks, within one year.