Before saying a lot (more) about baptism, did you read message #468 and consider those connections?

And while it is true that one fammily (Cornelius' in Acts 10) in the New Testament did receive the Holy Spirit prior to baptism, they were nevertheless commanded to be baptized, as is true in every story of conversion in the book of Acts. There is only the one incident reported of people receiving the Holy Spirit prior to baptism, and that a very special case to show that God would accept Gentiles, but every conversion story, including even the special event, incorporated baptism (Acts 2:38-41, 8:12-13, 8:36-38, 9:18, 22:16, 10:47-48, 16:15, 16:33, 18:8, 19:1-3).

The basic answer to why the emphasis is put on baptism is that
#1 -- God put it there and...
#2 -- human beings persistently rebel against God's teaching on this subject.

Nevertheless, God has elected to use immersion in water as the means of connecting a believer with blood of Jesus, with the spiritual metaphors of washing and new birth describing the process that God initiates for the obedient believer.

Acts 22:16
16 And now what are you waiting for? Get up, be baptized and wash your sins away, calling on his name.'
NIV

Titus 3:5
5 he saved us, not because of righteous things we had done, but because of his mercy. He saved us through the washing of rebirth and renewal by the Holy Spirit, NIV

Hebrews 10:22
22 let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water. NIV

Hebrews 12:24
24 to Jesus the mediator of a new covenant, and to the sprinkled blood that speaks a better word than the blood of Abel.
NIV

1 Peter 1:2
2 who have been chosen according to the foreknowledge of God the Father, through the sanctifying work of the Spirit, for obedience to Jesus Christ and sprinkling by his blood:

Grace and peace be yours in abundance.

NIV
Oh, and baptism is an action only if you are the actor. That is, the apostles were to baptise (active) but the believers are to be baptized (passive). Consider the language in Heb. 10:22 above, "having our bodies washed" and "having our hearts sprinkled". This language describes being a recipient, not a doer (as also in Titus 3:5). The doing is done by a baptizer, but primarily it is done by the Lord, not by the person being baptized, a passive submission to God's commands.

Nevertheless, while baptism is not a saving work, don't demean actions in God's economy. Faith does not displace the necessity of action. Rather, as James emphasizes, faith requires action...
James 2:18-23
18 But someone will say, "You have faith; I have deeds."
Show me your faith without deeds, and I will show you my faith by what I do. 19 You believe that there is one God. Good! Even the demons believe that-and shudder.
20 You foolish man, do you want evidence that faith without deeds is useless? 21 Was not our ancestor Abraham considered righteous for what he did when he offered his son Isaac on the altar? 22 You see that his faith and his actions were working together, and his faith was made complete by what he did. NIV