Stop trying to make the thing everyone else wants you to make. Make the thing you want to make. You're at you're best when you're passionate about what you're doing. Find your passion.
Mark Rosewater was the lead designer during the Scars of Mirrodin block. For some reason they were inspired by the movie "Planet of the Apes" where at the end of the movie it's revealed that the planet is Earth itself, in the future. They had the same idea for the second Mirrodin block, leave the surprise to the last set in the block. The players wouldn't know that Mirrodin has became New Phyrexia till the end. Mark had a hard time trying to make it work. Bill Rose, then Vice President of Research & Development of the game, made substancial changes to the design team in an attempt to make the set work. Bill enforced a six weeks deadline to Mark to have the set pass the approval phase, else the lead would have had to change. Both Mark and Bill felt the pressure and after some talk in private the answer to their struggles came.
After a weekend Mark came to conclude that they were making the wrong set. They were trying to tell the story backwards, beginning at the end of it. They wanted to tell the story of Mirrodin falling to the Phyrexians and they wanted to begin after the Phyrexian's victory, which is the story's climax. From that moment onwards Mark always asked himself "What am I passionate about? Why am I the best person to lead the design?". If he, as the lead, isn't excited how can he expect the players to be? That was what his position in making the game represents. He, as a leader, represents passion and excitement.
I'd begin by saying that Mark admits that he is egotistical. He's right that we have to at least like what we do, otherwise we can't succeed. However, as he admits, being stubborn brings up some issues because he often wants to push the game in a direction and that direction may not be the same as the other designers in the team want to go. Now about "Planet of the Apes" and Magic. The former is a story told in a movie and the latter is a story told with books, sites and cards. Sometimes we see a grand idea and try to replicate it, but we also want to add our own twist to it. It may work or it may not. In the case of Scars of Mirrodin it didn't. I'd say that when we see a great idea we often forget about what were the motives behind it. I'm sure that the process of creating a movie and a card game are very different from each other. What works in one environment may not in another.
I'd add that passion can be a double edged sword. The same passion that drives us forward can also be our own downfall. We can see that in Mark himself. Sometimes he pushes an idea forward with so much passion that the idea makes it to the final product. Then comes the players and their judgment is going to tell them whether that idea was a success or not. Mark has lots of examples from his career where some idea proved to be a failure. The long list of banned cards includes many of which Mark have created. I can certainly relate to that in terms of level design. I can recall levels in which I had an idea and wanted to go forward with it, till that idea proved to be a failure and I had to abandon it. About stop trying to make what others want you to make I'd be careful with taking this to the letter. One example is admission exams. They are often unfair but if there is no other way to get in, we don't have much of a choice other than preparing for it.
To conclude, passion is a strong driving force and we all must love something. But there is a threshold where excessive passion or love is dangerous. There is a very broad discussion that relates our egos with mental health and society, but that's way beyond my reach for this page. I'd just say that Mark's lesson relates to self-love, because the example he gave is about admiring something or someone and trying so hard to replicate it or be that person that we lose ourselves and could enter in a delusional state.
Bottom note: Mark asked himself "Why am I the best person to make this set?" The answer could very well be "you aren't", in which case we have to fight our own egos because if that's the case, then we must step down.
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