Nah, it doesn't really matter for consumers. It didn't really matter when 7 was new, so how could it matter now. It's just not a good thing having lots of legacy stuff you don't need:
* more updates - everything that's there can have bugs and vulnerabilities, whether you use it or not
* potentially more stuff to load from disk, which can make things slower or more memory intensive
* more disk space
None of these things by itself are really crucial for you, the user. You can compensate for most of these, for example with an SSD and a fast internet connection. It's something like the engine of your car - if you just want it to move you around, you can say "I don't care how it works and how inefficient it is as long as it doesn't break".
But if you are concerned with the internals, for example because you develop the next version of Windows, or have to manage lots of installations or virtual machines, cruft is expensive.
And not fun - Microsoft got real problems by losing some of their Kernel developers, because it's allegedly such a pain doing anything there. There are some strong deficiencies in critical parts like file access, but nobody dares to address those because of all the stuff being piled up on top you could break by fixing it, and you're not even getting an immediate payoff by it.
Another example: https://superuser.com/questions/8900...so-slow/935644
Even without understanding what GDR, LDR versions of updates and WOW64 are and how the component model of Windows works, it should be clear that having to keep many redundant versions of files and their updates is not a nice thing. The reason why every feature update of Windows 10 just reinstalls the whole system, is to reset the system's Windows Update patch level: they realized they just couldn't maintain another OS like Win7 for a decade just with Windows Update and the occasional Service Pack.
Considering Windows Update is such a mess, they need to get Windows more modularised. But in order to get from something like Win7 to something like Linux, you first have to start by throwing stuff out and reimplement these things as modules / standalone programs.
In a perfect world you would be able to only install the Windows components you need. For example, current versions allow you to install Windows with a heavily reduced graphics system for server use. This eliminates like half of the monthly security updates which is great for administrators. Similar stuff could be useful for home users - you don't need Domains or Active Directory? Just leave it out! Having a problem with the firewall? Install this beta version! WLAN problems? Try this third party package! And they could develop those things independently from another and release better versions when they are ready. Currently that's just not possible. With Linux, where the Kernel gets developed much more separated from all the stuff around, you can have a fully working operating system with office and everything with like 4GB. But getting there takes time and causes breakage. As proven by Windows 8, 8.1 and 10. And it doesn't help when the marketing front wants to push Phones and Tablets at the same time...
So if you ask me, Windows 10 is Microsoft's strategy to re-implement and restructure major parts of Windows in a sort of semi-agile way, which means while it's being used. The "next big thing" will happen when this is done. I don't see that in the next 3 to 5 years. That is just my opinion of course.