First: We must be careful about fair housing laws. Housing discrimination is illegal in nearly all housing, including private housing, public housing, and housing that receives federal funding. The Fair Housing Act protects people from discrimination when they are renting or buying a home, getting a mortgage, seeking housing assistance, or engaging in other housing-related activities. The Fair Housing Act prohibits discrimination in housing because of: Race, Color, National Origin, Religion, Sex, Familial Status, Disability

Second: Some sellers just want to unload a house. Others want to know their house and its functions and nostalgia will be preserved by the next occupant.

Third: A buyer's image and words are a powerful tool that could easily rub a seller the wrong way. Strategically it's a risky move. You don't know how the seller will perceive the image(s) and descriptions you include and it could kill a potentially successful deal.  Maybe the seller hates dogs. Maybe they think stripes don't work on you. Maybe you describe your intentions for the home/property in such a way that leaves a bad taste in seller's mouth. 

Fourth: Are you gushing about something that the seller could use as leverage against you in negotiations? There goes your poker face...

I'm not against a buyer carefully constructed letter that appeals to a sellers heart and mind. After all, real estate is extremely emotional and often financially sensitive for many people. However, it's best to leave out the letter if you can't clearly avoid fair housing topics. Without a doubt, you should leave the photo out. 

It's the seller's their right to see all documentation accompanying the offer but listing agents should discuss with the seller in advance how they want to handle letters to avoid any risk around fair housing/discrimination. If the seller is choosing not to look at letters, their agent should let buyer agents know.