I write software for a living, I can't agree with you, I want to get paid for writing commercial software.
You got paid when you wrote the software for the high end device. The way the company finances that and how it reflects on its customers doesn't directly affect you.
It's easier to make that argument for the frequency unlock, which is very obviously handicapping a device for the sole purposes of market segmentation and future revenue stream. It's clever, effective, but it feels a bit skeevy. Charging for decoding modules and other software features is a different matter, you're adding functionality, not just de-restricting.
I happily disagree with you. The decoding modules are, like the frequency capabilities, already there, they are just turned off without the correct key. I don't see that being different from the frequency unlock.
This depends a bit on the options, let's see what Rigol offers.
Frequency capability is determined 100% by hardware, there is no additional software work involved to make use of it. So if the hardware I bought is capable of a certain frequency but the manufacturer tries to make me pay extra for it then I clearly feel robbed. Same for memory, it's there in the machine, I've paid for it, but they lock it out for no good reason.
Advanced trigger, serial decoding are software-only features, so there it makes more sense to ask for extra payment - BUT it should be reasonable, and the problem is that it usually isn't. If you can build an entire scope and its huge firmware and sell it for $400, then the comparatively tiny amount of work your engineers had to do to add decoding of 4 serial protocols to the existing firmware base certainly isn't worth $174.
I mean, I can buy a full-fledged product that includes hardware and dedicated software that did not have a base developed for another already marketed application and does much more than that for $100... so that pricing simply makes no sense and can't appear in any other way than price gouging.
Another way to see it is that by having serial decoding as an option it is obvious only a fraction of users will buy it, say 10%. It means that had they shipped it by default and priced it for same income on that feature each scope would be only $17.4 more. That's the real price of the feature. I'd happily pay $17.4 more for it even if I didn't use it, and I doubt anybody would complain about it being an excessively expensive feature they don't want. They'd do more good by selling the scope for a mere 4% more and allowing everybody to make use of a tool rather than restrict its access by asking for a disproportionate amount to a small number of users. Given that decision of theirs that appear excessievely stupid to me, I won't feel bad hacking the $17.4 feature that should have been built-in in the first place.
I certainly understand the ways a company might use to attract customers, offer devices cheaper than they can be made for and recouping costs somewhere else etc, but ultimately it is their decision of how much they deviate from "reasonable" pricing and how it affects their customers' perception. If they want to go with it even if it feels so wrong, so be it, and the consequence is that people will try to "correct" that if they can. It is totally avoidable, but in the end it makes people talk, and as previously said there is a gain from that as well that they are certainly factoring in.