Take the Levites -- should 'take' have more than null value?

Summary: According to Rashi and according to Ibn Ezra, why does "take the Levites" mean anything? Can't it be a sort of preparatory verb for the purification found later in the pasuk? An answer, I think.

Post: Towards the start of Behaalotecha, we have:

ו  קַח, אֶת-הַלְוִיִּם, מִתּוֹךְ, בְּנֵי יִשְׂרָאֵל; וְטִהַרְתָּ, אֹתָם.

6 'Take the Levites from among the children of Israel, and cleanse them.

Rashi writes:

Take the Levites: Take them with words: You are fortunate in that you have merited to become attendants of the Omnipresent. — [Torath Kohanim 8:165, Midrash Aggadah]

קח את הלוים: קחם בדברים, אשריכם שתזכו להיות שמשים למקום:

This may be peshat, or may be midrash. It responds to a peshat concern, as we shall see -- Ibn Ezra addresses the phrase. But the explanation is drawn from a midrash, and is not the most apparent explanation from the simple text. Compare with parashat Korach, and Rashi there:

1. Korah the son of Izhar, the son of Kohath, the son of Levi took [himself to one side] along with Dathan and Abiram, the sons of Eliab, and On the son of Peleth, descendants of Reuben.		א. וַיִּקַּח קֹרַח בֶּן יִצְהָר בֶּן קְהָת בֶּן לֵוִי וְדָתָן וַאֲבִירָם בְּנֵי אֱלִיאָב וְאוֹן בֶּן פֶּלֶת בְּנֵי רְאוּבֵן:
Korah… took: This portion is beautifully expounded on in the Midrash of R. Tanchuma, [as follows]:		ויקח קרח: פרשה זו יפה נדרשת במדרש רבי תנחומא:
Korah… took: He took himself to one side to dissociate himself from the congregation, to contest the [appointment of Aaron to the] kehunah. This is what Onkelos means when he renders it וְאִתְפְּלֵג,“and he separated himself.” He separated himself from the congregation to persist in a dispute. Similarly, מה יקחך לבך, “Why does your heart take you away?” (Job 15:12) meaning, it removes you, to isolate you from others (Midrash Tanchuma Korach 2). Another explanation: He attracted the heads of the Sanhedrin among them with amicable words. Similarly, “Take Aaron [with words]” (20:25); “Take words with you” (Hosea 14:3) (Midrash Tanchuma Korach 1). - [Num. Rabbah 18:2]		ויקח קרח: לקח את עצמו לצד אחד להיות נחלק מתוך העדה לעורר על הכהונה, וזהו שתרגם אונקלוס ואתפלג נחלק משאר העדה להחזיק במחלוקת, וכן (איוב טו, יב) מה יקחך לבך, לוקח אותך להפליגך משאר בני אדם. דבר אחר ויקח קרח משך ראשי סנהדראות שבהם בדברים, כמו שנאמר (במדבר כ, כה) קח את אהרן, (הושע יד, ג) קחו עמכם דברים:

This is not just a midrashic concern, giving Rashi an excuse to cite a midrash. Ibn Ezra appears concerned by this as well. Thus, Ibn Ezra writes:

[ח, ו]
קח את הלוים מתוך בני ישראל -כי מעורבים היו וכן כל השבטים קודם שיסעו אל הדרך מהר סיני.

Take them from amidst the Bnei Yisrael, because they are mixed together when encamped.

I would not have felt compelled to say this. Rather, I would have simply understood kach as having almost a null value, where the point is to designate a group before describing the action to it. "Take an egg and beat it", as opposed to "beat an egg". That is, that it plays a syntactic role but no semantic role. Yet Ibn Ezra doesn't say this, and instead interprets it. What is bothering Rashi, and what is bothering Ibn Ezra?

It could simply be that he doesn't regard this as a linguistic possibility, and so there must be some meaning to this. Alternatively, something in context informs him that this has more than null value.

If we are looking at context, I would assume that the following is what drives it. Firstly, the words מִתּוֹךְ בְּנֵי יִשְׂרָאֵל in the pasuk appear to indicate that it is not just selection of the object in preparation for introducing the verb. Secondly, later in that perek we encounter

טז  כִּי נְתֻנִים נְתֻנִים הֵמָּה לִי, מִתּוֹךְ בְּנֵי יִשְׂרָאֵל:  תַּחַת פִּטְרַת כָּל-רֶחֶם בְּכוֹר כֹּל, מִבְּנֵי יִשְׂרָאֵל--לָקַחְתִּי אֹתָם, לִי.

16 For they are wholly given unto Me from among the children of Israel; instead of all that openeth the womb, even the first-born of all the children of Israel, have I taken them unto Me.

The words at the end of this bracketing, of כִּי נְתֻנִים נְתֻנִים הֵמָּה לִי מִתּוֹךְ בְּנֵי יִשְׂרָאֵל indicates that there was indeed a taking and giving from among the children of Israel.

(As to why Rashi does not understand this as literal taking, besides the fact that this is a midrash he is citing, the most literal is not always the best peshat. One does not literally take the person to some location, doesn't lift them up, and doesn't really acquire that person. Even though it is arguable here that that is precisely what happens in this instance. Rather, it means to gather them to your purpose, something often done with words.)