Why do people not use the numpad? (TKL and custom keyboards)
Many custom keyboards lack the classic numpad, as you may have noticed. That's both a trend and a deliberate consideration, but if you're new to custom mechanical keyboards, it might irritate you.
The majority of popular keyboards showing up on Youtube, Reddit, and Instagram come in fancy tenkeyless (TKL), 60% and even smaller form factors, stripped off their actual physical numpad.
What's going on, and don't these people miss having a numpad to type numbers on?
Whether you regularly use a physical numpad or can live happily without one, depends on your job, workflow and typing habits.
The point is, you have to figure it out on your own.
"Desk space" is the most prevalent answer if you ask for explanation. In fact, most individuals, particularly gamers, barely ever touch the numpad. For them, the numpad is only an annoyance interfering with mouse movement.
Btw, the numpad is arguably on the wrong side of the keyboard, and that's just one of the many unreasonable "features" of the standard keyboard.
Early terminal keyboards simply copied typewriters. Although there were no standards (before mid '80s), because of the overrepresented data-entry tasks designers put the numpad usually on the right. And that made sense since there was no computer mouse available back then. Thus, no interference.
But as soon as mice became common, we should have put the numpad on the left – or detach it completely from the keyboard.
This inconsistency is only one reason for people and manufacturers embracing tenkeyless designs.
Price and manufacturing considerations
In fact, it is much cheaper and easier to build custom keyboards in smaller form factors. This is especially true if you have to 3D print the case, but those 17-20 extra caps, switches (and optionally hotswap sockets, LEDs, diodes, etc.) can significantly increase the budget too.
(Just think about it: that's +30% keys and cost compared to a 60% keyboard and nearly double the price of a 40% one.)
Furthermore, a fullsize keyboard may necessitate a far more expensive controller: the cheapest Pro Micro is only capable to handle up to 100 switches (well, theoretically, and by hacking the LED pins).
That means you have to replace a cheap $3 (pre-Covid price) Chinese Pro Micro from Aliexpress with one of the $20+ alternatives.
Also, we can assume that enthusiasts who design and build their own keyboards know their typing habits very well and can decide whether they need the numpad or prefer a smaller keyboard instead. (At the very least, your first step into custom keyboard territory should be to critically observe and investigate your typing habits.)
Finally, you can retain the functionality of the numpad without having a physical one on your keyboard.
Putting it on a dedicated logical layer allows you to access all of the functions (or even more) without raising your hands and taking up more space, which is what people with ergonomic keyboard designs do.
This way, you can also improve the classic numpad arrangement. As a data entry tool, it is severely lacking keys like tab, :, $, %, etc. Of course, you should fine-tine it depending on your profession and workflow.
Check my layout (layer 2 and 3) at keyboard-layout-editor.com to have an idea what can be done to improve your efficiency.
Because I enter a lot of dates, the ability to type a proper ISO datetime value without raising my hand may be an important design goal in this case.
However, you may have entirely different needs, which is where programmable keyboards, open source firmware like QMK, and remapping some keys may come in handy.
That said, if you know you would regularly use a dedicated physical numpad, go ahead and get one (fullsize keyboard or a separate numpad).
However, if you only do data entry on a very infrequent basis and think numbers on a logical layer will do the job, feel free to embrace smaller form factors.
Thank you for your time! I hope this helps to explain why so many people don't use the numpad and the traditional fullsize keyboard layout.