I read through all the comments and feel that a significant element of the movie was mostly overlooked -- the relationship that formed between Whale and Boone was not as one-sided as many have chosen to view it. While the movie appears to focus on James Whale's transformation into a human being at peace with his mortality, the more powerful dramatic transformation takes place with Clay Boone's character.
Clayton Boone inadvertently provided James Whale a means for revisiting and perhaps coming to terms with his past. More importantly, Boone's unexpected pity in the face of Whale's intentionally uncomfortable verbal and physical sexual assaults in effect provided Whale with the strength to end his life on his terms.
But what did Clayton Boone receive from this relationship? Boone is the son of an alcoholic father, emotionally confused and unable to connect with others (re: Frankenstein). His burgeoning friendship with Whale was a means for him to try yet again to understand and come to terms with his roiled emotions stemming from childhood. Boone failed to please his alcoholic tyrant Father (indeed, a Sisyphean task since children of alcoholics are doomed to fail in meeting the perceived emotional needs of the abusive parent), and thus Whale represents another Father figure for Boone, seemingly as impenetrable and emotionally unavailable as Boone's own father.
This film is actually more about a young man growing up and coming to terms with himself. However the notion that all Boone needed was to confront his homosexual fears and overcome his rigid concept of manhood is off target. Boone is still trapped in adolescence because he is desperately trying to please his father; this makes the willing commitment to befriend Whale despite his sporadically abusive behavior all the more realistic. And the removing of the towel near the end is a watershed moment in which victim opens up once more to the abuser in a moment of complete vulnerability and trust. That his trust is betrayed (as it must have been so many times before by the alcoholic parent in his life) is heartbreaking, and yet both men recover and acknowledge friendship, platonic love and mutual respect in the aftermath. In the process of reliving his childhood torment through a Father-Son relationship with James Whale it is Clayton Boone who transforms himself and is fulfilled through Whale's friendship and shared wounds from an over demanding father. Whale's suicide at the end was not a reaction to failed lust for Boone -- far from it. His suicide was borne from the strength and clarity he derived from Boone's compassion, allowing Whale to face his mortality and willingly make peace with his past.
I understand that many feel the ending scene with Boone stomping about in the rain like Frankenstein was unnecessary and over the top. But showing a contented Boone who had obviously progressed from one-dimensional relationships to become a caring father and husband himself was the most important story element in the movie. The James Whale character in the movie may have thought himself a monster, a sexual predator with few redeeming qualities, but before dying he made a connection with another wounded soul, enabling both to heal. Whale's own redemption may have been the A plot of the movie, but Clayton Boone learning to sort out his confusion and pain was the B plot and the exclamation point in the film's final scene. Watching him playfully 'Frankenstein-about' in the rain in recognition and celebration of the relationship that helped him achieve fulfillment was a celebratory moment, and not an unfortunate throw-in to appeal to typical Hollywood standards.