For the Romantics, the central issue of Shakespeare's play is one of targeting the character fault that prevents Hamlet from accomplishing his assigned task: be it inner conflict or an excessively sensitive nature.

The argument upon which the Romantic critics relied is a modern restatement of the notion of the "tragic flaw." This notion, based upon a misunderstanding of Aristotle's Poetics, was popularized during the Renaissance and remained part of the cannon of dramatic theory thereafter. According to this theory, the tragic hero possesses an innate goodness and nobility of character which is sabotaged by some psychological weakness that eventually contributes to his downfall. Thus a "mole of nature" in an otherwise virtuous person leads to their undoing. For the Romantics, this was clearly believed to be Hamlet's inability of act out what they understood to be the need for revenge. Typically, Hamlet was seen as someone who thought excessively -- so much so that thinking became a deterrent for action. Those who cling to this notion, found ample chapter and verse to cite in Hamlet

Edwin Forrest - 1835

Why, then 'tis non to you, there is nothing either good or bad but thinking makes it so. To me it is a prison.  - II.ii.253

Thus conscience does make cowards of us all,
And thus the native hue of resolution
Is sicklied o'er with the pale cast of thought,
And enterprises of great pitch and moment,
With this regard their currents turn awry,
And lose the name of action.  - III.i.83-88