Why doesn't the KJV indicate the speakers in Song of Solomon?

Newer translations tend to indicate the speakers in Song of Solomon with tags such as “Lover,” “Beloved,” “He,” “She,” “Shulamite,” “Beloved,” “Friends,” “Relatives,” “Chorus.”  The KJV does not have such tags, which appears to make the text harder to follow.  But the original Hebrew is one continuous text just like in the KJV.  In Hebrew, the speakers can often be identified by the gendered pronouns; but not always.  Scholars disagree as to who the speakers are in some portions of the Song.  Following a label inserted by the editor of a translation could become a distraction to exploring the various interpretations of this mysterious narrative.  The following are some of those examples:

Song of Solomon 1:4

Here in the same block of text the pronoun switches back and forth between "me" (singular) and "we" (plural): "Draw me, we will run after thee: the king hath brought me into his chambers: we will be glad and rejoice in thee, we will remember thy love mo
Song of Solomon 2:1

The line, "I am the rose of Sharon, and the lily of the valleys" is attributed to the bride in the ESV, NIV, NASB and NKJV.  However, the text is ambiguous and the line could be attributed to the groom.  Several scholars throughout history have understood the titles, "The Rose of Sharon" and "The Lily of the Valleys", as titles for Christ, who is the groom of the Church.  These titles are included in the famous list of the names of Jesus Christ compiled by Herbert Lockyer.  These are understood as Christ's titles in John Wesley's Explanatory Notes.  Most commentaries will admit that the text is ambiguous.  The KJV preserves this rightful ambiguity.

Song of Solomon 8:5

In the NKJV the speaker who says, "I awakened you under the apple tree..." in verse 8:5b is a relative of the bride. But in the NIV that same line, "Under the apple tree I roused you," is attributed to the bride. To complicate the matter further, the previous line, "Who is this that cometh up from the wilderness..." (8:5a) in the NIV and NKJV is attributed to a male speaker but the ESV attributes it to the bride. Moreover, the NIV indicates this male speaker as a "friend", not a brother.

Song of Solomon 8:8

The ESV attributes 8:8-9 to "Others", the NIV attributes these verses to "Friends".  The NKJV attributes the verses to "Brothers".  However, the heading in the original Scofield Bible attributes verse 8 to the bride and verse 9 to the bridegroom.

The love triangle theory

Some have interpreted Song of Solomon as a portrayal of a love triangle consisting of King Solomon, the Shulamite and a shepherd lover.  This is called the "Shepherd Theory".  Whether or not one agrees with the theory, the theory is an interesting one and deserves to be considered.  However, translations with the traditional labels of only two lovers make it impossible to consider the merits of this Shepherd Theory.

Allegorical application

The Song could also be read as an allegory of God’s love for Israel or the Church, so a plain text version of the Song can be useful for that purpose.  Although translations that attempt to identity the speaker for each line are at best useful study tools, a translation such as the KJV that provides only the plain text is useful for developing one’s own understanding of the speakers in the Song without the interference of subjective tags.