blessing - Why do we recite 'Borei Pri Ha'etz ' on grapes?

One thing I have always wondered is why we recite Ha'etz over grapes.

First, grapes grow on a vine, so why do we say 'borei pri hagafen' only after the fruit has been processed. Second, grapes generally grow close to the ground so I would then think the bracha would be ha'adama. One might then argue that since it is a vine, it can grow high on a trellis or that it is a perennial. However we make ha'adama on strawberries which are also perennial vines.

Is the reason somehow related to the fact that ha'etz is higher on the bracha hierarchy, and that since grapes (in wine form) serve ritual purpose we would like to give them a 'higher' bracha?

Answer

In regards to your "first" question, the reason that we do not say hagafen before they are processed should really be asked the other way around, which is why do we make hagafen after it is processed, as opposed to any other fruit which does not get a more specialized blessing? The answer is given in Berachos 35b that since wine is סעיד ומשמח, typically translated as sating and gladdening, it gets a special blessing.

ויין ישמח לבב אנוש ולחם לבב אנוש יסעד וגו' נהמא הוא דסעיד חמרא לא סעיד אלא חמרא אית ביה תרתי סעיד ומשמח

So grapes, which have not reached that stage at which they are סעיד ומשמח remain in the same camp as all other fruit which gets a more general blessing of borei pri ha'etz.

Which brings us to your second question, why is it a borei pri ha'etz? The basic requirement of borei pri ha'etz is being perennial, as you mentioned, based on Berachos 40a.

היכא מברכינן בורא פרי העץ היכא דכי שקלת ליה לפירי איתיה לגווזא והדר מפיק

Tosefos there actually suggests that all berries should be borei pri ha'etz based on that standard, however he brings from the Yerushalmi that fruit of brambles/thorn bushes are pri ha'adama.

איתיה לגווזא והדר אתי. מהכא נראה דתותים ופריזיי"ש ובונטונ"ש וכיוצא בהן צריכין לברך עליהם בורא פרי העץ שהרי דרך העץ להתקיים ימים רבים וכי שקיל הפרי בשנה זו הדר אתי פרי באותו העץ עצמו מיהו הרב רבי מנחם הביא ראיה מירושלמי דמסכת כלאים דמברכין על כל מיני דאטד בורא פרי האדמה דקאמר התם ההגין ואטדין מין אילן הם ואינן כלאים בכרם ופריך והתניא אלו הן מיני דשאים הקונדס והאטד ומשני תמן לברכה והכא לכלאים אלמא לענין ברכה מיני דשאין ומיהו לדברי הכל פריזיי"ש צריך לברך עליהם בפה"ע דאינו גדל על אטדין ועצו מתקיים משנה לשנה

A grape vine is very different than (your example of) a strawberry vine, as the grape vine is long, and when latticed actually looks much like a tree. See a picture here. Strawberries grow on small stumpy bushes (like this), what Tosefos is calling an אטד, and are pri ha'adama.