In HW, RI and Vengeance gave you Wrath/Abandon stacks, which you can think of as 10 gauge in modern terms. IIRC, in order to land a third FC under Berserk, you needed to pop one of these two defensive cooldowns per Berserk (and both in your opener). So it was generally advantageous to line up periods where a WAR was actively taking damage with their burst window, since those cooldowns were being used anyways. I've always thought that was a fun and unique form of skill expression for WAR. Granted, I also thought that the idea of 'building up' resources towards a planned Berserk burst window was another really interesting form of skill expression, but players were apparently really uncomfortable with that sort of gameplay, leading to the 4.2 Unga Bunga changes that have carried on into the present day.

It's hard to gauge what players are going to find 'too difficult', but it's usually better for skill expression to be rewarded rather than penalizing a lack thereof. If IR rewarded you for using defensives while it was up, or provided a synergistic mitigation benefit, then you might get some of that gameplay back without penalizing players who don't know fight timings well enough to line up their windows correctly. It also fits in with that 'unkillable' berserker rage.