We suffer of the same illness.
Jokes apart, I share your thoughts about how those games were important to me when I was younger. For example, I think that the humor of MI1 and MI2, mostly conveyed by the characters with expressionless faces (due to the lack of details) contributed to build my appreciation for deadpan humor.
Another strong repercussion of Ron’s stories is that I’m clearly obsessed with the freakin’ secret, to the point that I become annoying when I show to other people my fixation for it. 
Still, regardless of how important those games were for me, I don’t think that my mind will automatically accept anything for the new chapter of the series. The reason is that I have always been strongly influenced by the visuals of any game, in a disproportionate way.
For example, I did play MI4 but I can’t remember if I ever finished it! For me, the graphic style of the characters was very unpleasant. The art style of that game had the power to switch off my interest.
The opposite is also true: Benoit Sokal’s Sinking Island isn’t considered a very well made game. For example, there is a lot of backtracking, especially in the later chapters, but for me the visuals are stunning and wandering around that environment is only a pleasure for me.
Thimbleweed Park is another example: I followed the development of the game since its beginning, but I didn’t back the Kickstarter, because I didn’t like Winnick’s art style. As soon as some examples of Mark Ferrari’s backgrounds were shown, I immediately backed the project, through the official website.
Now, being aware of the weight that I put on the art style of games, I have decided to approach Return to Monkey Island with a pinch of detachment, despite of my three-headed-monkey t-shirt and despite the importance that MI1 and MI2 had for me.
Detachment is the only way for my mind to give this game a chance. Statements like “the art always threw [off] people for the first hour” and my first impressions of the shared screenshots don’t go in a particularly pleasant direction for me, so I have to build a bit of distance from it, in the form of the thought “it’s just another MI game”.
I have accepted the fact that this is not my game and that probably I will have some trouble feeling it as mine, as I felt with MI1 and MI2. It’s the developers’ game, and I respect that.
I would have preferred that the decision to shock people had been made by choosing hip hop as the music style, however. In that case, I could have just turned off the audio. 