For the majority of his fans, there was no positive side to his lip-sync during the HIStory Tour.
With the exception of ‘Wanna Be Startin' Somethin'’, ‘The Jackson 5 Medley’, the brief ‘In The Closet’ spoken part and some live ad-libs here and there, he lip-synced all the other songs during that tour, which is inexcusable when you pay in order to attend and watch a live concert.
Also, his lip-sync on that tour was too obvious and annoying (especially in ballads/mid-tempo songs), and it even made him at times look embarrassed on stage when, for example, he was trying to cover his mouth with his hands, or with his long hair, or even with his body posture by leaning forward while lip-syncing.
If the HIStory Tour happened today with the same amount of lip-sync, it would have been a public/media disaster for him, in terms of unfavourable press headlines (such as, the ‘King Of Lip-Sync’ headline), audience demanding ticket refunds, etc.
The argument that he had to lip-sync during the HIStory Tour because he was also dancing a lot at the same time is not a valid one, because few years earlier he proved during the Dangerous Tour that he could dance a lot and sing live at the same time (more than half of the performed songs of the Dangerous Tour were sung live, and many of them were energetic songs).