This argument is too general. There are 4 things that Samsung was "doing wrong" in my opinion, according to what I want to see in devices, and this eliminated two of them. The other two (physical button and software) will still prevent me from buying a Samsung phone, but this decision made me regain some respect for their design philosophy.
Removable battery is an engineering and resource mistake - removing this "option" opens the door to many more benefits and goes one step further to eliminating the "drain it all the way" mistake that many users make more often when they can just hot swap - an action alone which wreaks havoc on Android's ability to anticipate usage and manage background tasks. I understand that some people want this option and have no issue with that - for me, it is smarter to close this thing off.
MicroSD card slot is an engineering and resource mistake that allows for security and performance risks not otherwise introduced. Every second spent coding for this option, not to mention the materials and engineering compromises necessary to have it present, falls into the opportunity cost category - time and money not spent on improving the device or software or health of the company (which allows for it to become more creative, etc).
Physical home buttons, etc require materials, engineering compromises, consume physical space and require software resources to enable them. This "feature" was made obsolete in 2011 and seeing devices still released with it is somewhat disappointing. Again, I realize some users prefer this - I just simply disagree. It speaks to a design that detracts from design evolution and utility, rather than helping move the cause forward.
Software - Samsung's TouchWiz comes rich with many, many features. None of them are quite as useful as what Moto brings and in fact many of them are system resource intensive messes with very little value add to most users. Throw everything on the wall and see what sticks is a poor substitute for understanding your market and designing software that meets their needs and raises their expectations of how their devices should/could interact with them. Android as a system is moving towards a concept that resembles getting the software out of the way of content, people, etc. Samsung is one of the biggest offenders when it comes to resisting the more modern perspectives and all three of the above are physical manifestations of this apparent belligerence.
Now, obviously "Samsung" doesn't have an attitude, it responds to market forces in whatever way it believes it can best capitalize - so in fact, Samsung's failings of aspiration are more in fact reflections of the poor atmosphere of their consumer base - many of which were making decisions based on very old software versions running on very cheap (in price and quality) devices. These signals must have been hard to overcome, but I for one am glad that Samsung has taken this tiny step towards rejoining the present course of the platform.