Exactly. It doesn't matter how fast your processor is if it's got nothing to do. It could be 3 GHz, 4 GHz, or 5 GHz... it doesn't matter. If it's got nothing to do then it's wasted clock cycles and most importantly, wasted electricity. But we're going off on a tangent here.
Basically, if you're working with huge media files like large images in Photoshop or huge video files in Adobe Premier, then yes... sequential reads and writes are going to be something you're going to want to worry about especially if you're having to scrub the timeline a lot. However, for the average user, CrystalDiskMark's RND4K Q1T1 is the number you're going to want to pay close attention to since that will give you a much better idea of how much faster (compared to the traditional HDD) your system will be.
In essence it's why I have no want to replace my current Samsung 970 EVO. It gives me the performance I want. What more could I want? Replacing it would be fixing something that isn't broken.
Except I replaced my 1TB 970 EVO (that I paid a whopping $700 CAD for on launch and felt regret over ever since) with 2 x 1TB ADATA SX8200 Pro for less. I do enjoy the extra storage space. I have a 2TB Intel 660p I picked up for cheap ($190 USD) also. It's fine but slows down in a way the Adata and Samsung don't.