I think if we look at some of the other usages of πρᾳότης (and it's adjective) it could shed some light on your question.
Let's first consider the beatitude Μακάριοι οἱ πρᾳεῖς· ὅτι αὐτοὶ κληρονομήσουσιν τὴν γῆν..Mt.5:5 For now, let's just observe that an " inheritance " is something that is given.
For the ὅτι πρᾷός εἰμι καὶ ταπεινὸς τῇ καρδίᾳ· καὶ εὑρήσετε ἀνάπαυσιν ταῖς ψυχαῖς ὑμῶν. of Mt.11:29, I've always understood this to mean "not overbearing", The "lean on me" is a passive offering rather than an active one. If it had been written actively, would have been something like "I will support you" (using a verb like in ὑποστηρίζει κύριος πάντας τοὺς καταπίπτοντας Ps.144:14 "The Lord supports all those who fall".). Also, it says, "You will find rest" not "I will give you rest" or "I will show you the way to find rest" as in the εἰς τόπον χλόης ἐκεῖ με κατεσκήνωσεν ἐπὶ ὕδατος ἀναπαύσεως ἐξέθρεψέν με "he settles me in a place of lush (green) pasture nourishing me beside the waters of rest" of Psalm 22:2.
In one of the other passages where this word is used, ἐν τῷ ἀφθάρτῳ τοῦ πρᾳέος καὶ ἡσυχίου πνεύματος, 1 Pt.3:4 I think that the two meanings πραΰς and ἡσύχιος are synonyms, with the first referring to the calmness in not needing to reach out to affect things and the second to be a quietness within oneself (pervading stillness / settled-ness), and I take them together to mean "a spirit that wants to understand things and deal with things within the intimacy of a close relationship and deep understanding", like what you see in couples who have the basic things of relationship settled at a given time and haven't got an antagonistic or competitive spirit.
For the noun, the passage Τί θέλετε; Ἐν ῥάβδῳ ἔλθω πρὸς ὑμᾶς, ἢ ἐν ἀγάπῃ πνεύματί τε πρᾳότητος at 1 Corinthians 4:2 suggests that the Corinthians are being given the option of changing themselves now, or of having the Apostle actively change them later (BTW, I really like what I heard one Bible teacher say about a rod (ῥάβδος), something like, "a shepherd can find a lot more intelligent things to do to a sheep with a rod other than just beating the sheep with it". In my thinking, that might include blocking the way to danger, beating wolves away, using the rod as a "gate"/"fence" to put the sheep on a good way)
The πρᾳότης, ἐγκράτεια of Galatians 5:23 in my opinion are the external (interpersonal) self restraint and the internal (passions and lusts like hunger/fear) self-restraint synonyms - meaning like control yourself to not force yourself on others and control yourself to not be driven by things and feelings that seem necessary from the point of view of the instant present, but perhaps in the future will not seem like they were so necessary.
In Galatians 6:1, I take ὑμεῖς οἱ πνευματικοὶ καταρτίζετε τὸν τοιοῦτον ἐν πνεύματι πρᾳότητος, σκοπῶν σεαυτὸν μὴ καὶ σὺ πειρασθῇς. to mean that the "spiritual" should help, but not force the repentant to return to righteousness. Like be patient enough to give a person time for the fruits of repentance to ripen in their heart.
In this regard, the μετὰ πάσης ταπεινοφροσύνης καὶ πρᾳότητος, μετὰ μακροθυμίας, ἀνεχόμενοι ἀλλήλων ἐν ἀγάπῃ, of Ephesians 4:2 means that we put up with each other without forcing our own foibles on each other. Everyone has his own character, upbringing and is at a different point in their walk with God, and age of life.
Following in this vein 2 Timothy 2:25 ἐν πρᾳότητι παιδεύοντα τοὺς ἀντιδιατιθεμένους· μήποτε δῷ αὐτοῖς ὁ θεὸς μετάνοιαν εἰς ἐπίγνωσιν ἀληθείας, sort of means "step back and let God".
The verse in James 3:13 Τίς σοφὸς καὶ ἐπιστήμων ἐν ὑμῖν; Δειξάτω ἐκ τῆς καλῆς ἀναστροφῆς τὰ ἔργα αὐτοῦ ἐν πραΰτητι σοφίας. Suggest that when we do (good) deeds, we should do them wisely, I think that "wisely" here means like 2 Corinthians 8:21 προνοούμενοι καλὰ οὐ μόνον ἐνώπιον κυρίου ἀλλὰ καὶ ἐνώπιον ἀνθρώπων.
The ἕτοιμοι δὲ ἀεὶ πρὸς ἀπολογίαν παντὶ τῷ αἰτοῦντι ὑμᾶς λόγον περὶ τῆς ἐν ὑμῖν ἐλπίδος, μετὰ πρᾳΰτητος καὶ φόβου· of 1 Peter 3:15 suggests that rather than running up the wicket and playing the ball on the front foot, we should be ready to give an apology after we are asked.
In conclusion, I think that in the verse you are asking about, Διὸ ἀποθέμενοι πᾶσαν ῥυπαρίαν καὶ περισσείαν κακίας, ἐν πρᾳΰτητι δέξασθε τὸν ἔμφυτον λόγον, τὸν δυνάμενον σῶσαι τὰς ψυχὰς ὑμῶν. James 1:21, has two parts, the first is active (based on ἀποτίθημι) and the second passive (based on δέχομαι). The above usages of πρᾳότης (and it's adjective) suggest that it should be used with a passive (non) action, so I feel that it may be possible that taking it with δέξασθε τὸν ἔμφυτον λόγον, τὸν δυνάμενον σῶσαι τὰς ψυχὰς ὑμῶν comes more naturally than with the ἀποθέμενοι πᾶσαν ῥυπαρίαν καὶ περισσείαν κακίας.
Sociolinguistic grammar question:
Why do people who say, "We have an attitude problem." talk about themselves in the plural?