You've really missed the point.
Yes, LaunchPad can be accessed those ways but there are other methods to access it that are easier, faster, and more intuitive using gestures.
MOREOVER, the point is that you can curate, filter, order, configure, massage the interface in a manner that suits the individual's workflow.
Having to learn how Apple has chosen to configure the interface is a substantial extra step that you've overlooked. And for people who want to understand the reasoning for a method to better predict how to use it going forward, there really is no way to confidently acclimate to this interface. Applications you will never use are adding substantial noise to the interface and apps you later install will rearrange the existing orientation.
If you're someone who only uses Spotlight to launch applications, nothing has changed for you. If you've never relied upon Launchpad as your primary productivity workflow, there is nothing you could positively contribute to this conversation. A core graphic user interface has been wholly deleted from the operating system with no similar replacement, for no apparent reason. The best you can do is try to understand that some people do not rely on a command line interface to launch applications and their brains work best in a dimension that can predict where things are for their ultimate productivity.
And by the way, had Spotlight been working properly for the past however many years, perhaps people would have learned to use it better. For me, the vast majority of the times, Spotlight can not find core applications like Calculator or Notes or Safari. The same can be said about Siri. If Apple released tools that worked predictably out of the gate, these tools would have a higher adoption rate.