Development time is more important than customer habit

Is a customer habit or request more important than development time?

The rise in modern User eXperience (UX) in applications have given customers more reasons to use their systems. Some startups have become successful by bringing a rich, simpler and better workflow to customers. An example is Odoo, previously known as OpenERP. Compared to traditional ERP systems such as SAP and Oracle, the workflow is much leaner and simpler to use, from installation, deployment to daily use.

Does this however means that a project manager can entertain every customer wants ? The authors of the bestselling book Rework tell to "Say NO By Default". That might be a counter intuitive decision, as it can drive away clients. Except for fundamental and business important changes, most of the remaining change requests are trivial and can be postponed for later or even canceled.

Development is costly, in terms of coding, testing and regression. Each change request or feature creeps add technological debt, which makes it more difficult to change on the long term - for example Microsoft Windows was rewritten using another set of technologies instead of continuing iterating the previous version.

The customer mostly probably does not know this details or can't realise the impact of their change. If the customer can change their behaviour, work flow or habit quite easily, it's better for them than having to code additional feature.

For instance, if a web application is developed to be compatible with Chrome and Firefox but the customer uses Microsoft Edge Browser - it's better for everyone that they change their browser than to cater for this browser - particularly given that Microsoft is going to soon replace Edge rendering machine with Chromium and Webkit.