Why would interpretation be needed?
It seems to me that a keyword in Revelation 1:3 is 'hear'. That is the following Greek word.
akouo
ak-oo'-o
a primary verb; to hear (in various senses):--give (in the) audience (of), come (to the ears), (shall) hear(-er, -ken), be noised, be reported, understand.
'Understand' appears to fit the meaning in verse 3, IMO anyway. As to pertaining to the book of Revelation, I do not see it being reasonable that one can just simply understand what is written in this book without it involving interpreting anything.
Take the following, for example.
Revelation 5:8 And when he had taken the book, the four beasts and four and twenty elders fell down before the Lamb, having every one of them harps, and golden vials full of odours, which are the prayers of saints.
How could anyone possibly know that the Lamb meant here is meaning Jesus, unless they have interpreted it to mean Him? IOW, unless one has already interpreted that the Lamb meant here is meaning Jesus, that could mean the Lamb could be meaning anyone or anything they want the Lamb to mean. Apparently, you don't seem to fully grasp what all interpreting something involves. And to suggest that Revelation 1:3 simply means the book of Revelation requires no interpreting of anything, this is not reasonable.
Maybe in your mind it is reasonable, yet, how can you possibly think that only what you have decided in your mind, this is the only way things have to be involving the book of Revelation, and not the way a billion professed Christians, for example, in opposition to that, think in their mind that this is the way things have to be involving the book of Revelation, that it has to be interpreted(meaning interpreted correctly of course) in order for one to actually hear(understand) the prophecies written in this book?