Good question. Because I am a native Japanese but I have never thought about it.
Although there would be some exceptions; in general, this is a Japanese expression to describe someone else.
If I translate it directly into English, it is gonna be like this.
私、たけしさんの事が好き = I like about Takeshi-san.
私は、あなたの事が好き = I like (all) about you.
Other examples for "~の事が(を、は)
あなたの事を教えて = tell me about yourself.
私の事は知らないでいい = you don't need to know about me.
You can say "あなたが好き" or "あなたの事が好き." They both means basically the same, even though like I explained that they mean "like" and "like about." We, the Japanese, use them as more or less as the same expression. However, if you use ~の事が, the expression sounds more like talking about specifically humanbeings. Because we dont say, 私は犬の事が好きです(I like about dogs) or 私はスイカの事が好きです(I like about water melon). "~が好きです" is more expression for general things and human, and "~の事が好きです" is tend to be used more specifically for humanbeings.