Looking at it again, I have to say it does rather come off as lecturing parents at large. The huge size of the "URGENT NOTICE !!!" ... Underlining Please Read (you know, just in case that wasn't enough?), and the rather colloquial " Enough Said " all come off as a bit admonishing and demanding. Not quite the stuff you might expect of co-equals who do appreciate your abilities to decide and improve stuff for your own kids with their best interests in mind... While it may be within the scope of her concerns to ask for action (it's hard to be certain exactly what or with how many kids she's talking about, but it may)... It's not very pretty or tactful.
Some of those parents who it doesn't apply to, might adopt the same tone of "Oh, shame, who could it be???" and take the perceived tone of the letter as a reason for more neighborly criticism and intrusion... Others might mount defensive reactions more along the lines of "I don't think this was for me, but I don't really appreciate receiving such a message [if indeed everyone needed to receive it at all, some would add] in quite this form."
The whole handwritten form doesn't look neutral or businesslike either. Again it feels a bit like tossing one's position around too casually. I can imagine parents thinking something along the lines of, "Oh you want to lecture me on this from a safe distance through your so-called 'official' letter that I have to sign and return or else (what exactly huh), and yet rather than type it you are satisfied to shoot off your big warnings with chummy handwritten script and colloquialisms like we're all high school buddies?" More generally, having so many changes in script size is kind of jarring to read (and the occasional missing period makes it a lot worse). I have to wonder if she isn't more used to writing for kids than adults. It's not the aesthetics I expect of a formal note to somewhat distant partners on an adult "business" matter like childrearing.
Again though, I wonder how many pre-K's are "seriously" organized places where teachers are given equipment or offices... Though that could be a community or institution problem, more than an individual teacher problem.